[wasm] Wasm TimeZoneInfo implementation VFS (#17760)

* [wasm][bcl] TimeZoneInfo implementation for WebAssembly to read from WASM VFS `/zoneinfo`.

- Remove `TimeZoneInfo.WebAssembly.cs` file
- Remove source dependencies on `TimeZoneInfo.WebAssembly.cs`.
- Modify TimeZoneInfo for specific WASM functionality
   - Default root directory is `zoneinfo`
   -  Add icall `mono_timezone_get_local_name` for WASM in CreateLocal
- Add icall implementation
   - ves_icall_System_TimeZoneInfo_mono_timezone_get_local_name

* [wasm][build] Add `-s FORCE_FILESYSTEM=1` to mono wasm runtime build

- Required so that it includes support for loading pre preload packages

Message when generating the zoneinfo data.
   > Remember to build the main file with  -s FORCE_FILESYSTEM=1  so that it includes support for loading this file package

* [wasm] zoneinfo data and support files.

- Three files for zoneinfo VFS support.
   - `mono-webassembly-zoneinfo-fs-smd.js.metadata` - This is the separate metadata output by emscripten file-packager.  Used to parse the zoneinfo data in non browser environments.  See `runtime-tests.js`
   - `mono-webassembly-zoneinfo-fs.js` - Output by emscripten file-packager that will be referenced by browser environments to load the zoneinfo data into the VFS at `/zoneinfo`
   - `zoneinfo.data` - The binary file output by emscripten file-packager.  The file contains the actual zoneinfo data loaded into the VFS and parsed by `TimeZoneInfo`.

* [wasm][driver] Add backing support for icall `mono_timezone_get_local_name`

* Add TimeZone info test.

* [wasm][packger] Add `-s FORCE_FILESYSTEM=1`

- Required so that it includes support for loading preload packages

Message when generating the zoneinfo data.
   > Remember to build the main file with  -s FORCE_FILESYSTEM=1  so that it includes support for loading this file package

* Fix AOT tzd test

* Remove commented code lines for `TimeZoneInfo.WebAssembly.cs` module

* Regenerated zone info without --no-heap-copy as it causes problems.  This will create a warning in browser for now.

* Add zoneinfo support files to package

* Fix TimeZoneInfo tests to use the `--enable-fs` packager parameter

* Add back icall implementation after rebase
   - ves_icall_System_TimeZoneInfo_mono_timezone_get_local_name

* Add back backing support for icall `mono_timezone_get_local_name` after rebase

* Fix build error

* Add back zoneinfo tests to Makefile after rebase

* Fix packager zoneinfo sample builds.

* Address review comment about volatile not needed

* Address review comment about volatile not needed

* Address review comment about volatile not needed

* Address review comment volatile not needed

1 files changed, 114 insertions, 0 deletions

diff --git a/sdks/wasm/tests/src/tzdtest.cs b/sdks/wasm/tests/src/tzdtest.cs
new file mode 100644
index 00000000000..b00070c694f
--- /dev/null
+++ b/sdks/wasm/tests/src/tzdtest.cs
@@ -0,0 +1,114 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Globalization;
+
+public class TZDTest {
+	static TimeZoneInfo _timeZoneInstance;
+	static string _timeZone;
+	public static void Main (String [] args)
+	{
+		var local = TimeZoneInfo.Local;
+		Console.WriteLine($"TimeZone: {local}");
+		var dt = DateTime.Now;
+		Console.WriteLine($"DateLocal: {dt}");
+		var utc = DateTime.UtcNow;
+		Console.WriteLine($"DateUTC: {utc}");
+
+		Console.WriteLine($"GetUserTime: {GetUserTime()}");
+		Console.WriteLine($"GetUtcUserTime: {GetUtcUserTime(dt)}");
+
+		DateTime localDate = DateTime.Now;
+		DateTime utcDate = DateTime.UtcNow;
+		String[] cultureNames = { "en-US", "en-GB", "fr-FR",
+								"de-DE", "ru-RU" } ;
+
+		foreach (var cultureName in cultureNames) {
+			var culture = new CultureInfo(cultureName);
+			Console.WriteLine("{0}:", culture.NativeName);
+			Console.WriteLine("   Local date and time: {0}, {1:G}",
+							localDate.ToString(culture), localDate.Kind);
+			Console.WriteLine("   UTC date and time: {0}, {1:G}\n",
+							utcDate.ToString(culture), utcDate.Kind);
+		}
+
+		var tzd = TimeZoneInfo.FindSystemTimeZoneById("US/Eastern");
+		Console.WriteLine($"TimeZone: {tzd}");
+
+		Console.WriteLine($"TimeZone: {TimeZoneInfo.FindSystemTimeZoneById("Pacific/Honolulu")}");
+		
+		var tzs = TimeZoneInfo.GetSystemTimeZones();
+		foreach(var tzi in tzs)
+		{
+			Console.WriteLine(tzi);
+		}
+	}
+
+	/// <summary>
+	/// Returns a UTC time in the user's specified timezone.
+	/// </summary>
+	/// <param name="utcTime">The utc time to convert</param>
+	/// <param name="timeZoneName">Name of the timezone (Eastern Standard Time)</param>
+	/// <returns>New local time</returns>
+	public static DateTime GetUserTime(DateTime? utcTime = null)
+	{
+		if (utcTime == null)
+			utcTime = DateTime.UtcNow;        
+			
+		return TimeZoneInfo.ConvertTimeFromUtc(utcTime.Value, TimeZoneInstance);
+	}
+
+	/// <summary>
+	/// Converts local server time to the user's timezone and
+	/// returns the UTC date.
+	/// 
+	/// Use this to convert user captured date inputs and convert
+	/// them to UTC.  
+	/// 
+	/// User input (their local time) comes in as local server time 
+	/// -> convert to user's timezone from server time
+	/// -> convert to UTC
+	/// </summary>
+	/// <param name="localServerTime"></param>
+	/// <returns></returns>
+	public static DateTime GetUtcUserTime(DateTime? localServerTime)
+	{
+		if (localServerTime == null)
+			localServerTime = DateTime.Now;
+
+		return TimeZoneInfo.ConvertTime(localServerTime.Value, TimeZoneInstance).ToUniversalTime();
+	}	
+
+	/// <summary>
+	/// The users TimeZone using .NET TimeZoneNames
+	/// </summary>
+	public static string TimeZone
+	{
+		get { return _timeZone; }
+		set
+		{
+			TimeZoneInstance = null;
+			_timeZone = value;
+		} 
+	}
+	public static TimeZoneInfo TimeZoneInstance
+	{
+		get
+		{
+			if (_timeZoneInstance == null)
+			{
+				try
+				{
+					_timeZoneInstance = TimeZoneInfo.FindSystemTimeZoneById(TimeZone);
+				}
+				catch
+				{
+					TimeZone = "Pacific/Honolulu";
+					_timeZoneInstance = TimeZoneInfo.FindSystemTimeZoneById(TimeZone);
+				}
+			}
+			return _timeZoneInstance;
+		}
+		private set { _timeZoneInstance = value; }
+	}
+}
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