Add regular expression support to list of user agents to exclude (#16766)

* Add regular expression support to list of user agents to exclude

- Added regex support to Administration -> Websites -> Settings ->
Global list of user agents to exclude
- Made sure old tests that use stripos() pass
- Added new tests
- Added a sentence to the inline help area about regex support
- Fixed a typo elsewhere as specified in the original issue.

Closes #14186.

Updated method and tests following code review

Update plugins/WebsiteMeasurable/MeasurableSettings.php

Co-authored-by: Stefan Giehl <stefan@matomo.org>

Update system tests

* Update screenshots for UI tests affected by the copy changes

1 files changed, 7 insertions, 2 deletions

diff --git a/core/Tracker/VisitExcluded.php b/core/Tracker/VisitExcluded.php
index 243618bc51..8d412cef26 100644
--- a/core/Tracker/VisitExcluded.php
+++ b/core/Tracker/VisitExcluded.php
@@ -349,12 +349,13 @@ class VisitExcluded
      * Returns true if the specified user agent should be excluded for the current site or not.
      *
      * Visits whose user agent string contains one of the excluded_user_agents strings for the
-     * site being tracked (or one of the global strings) will be excluded.
+     * site being tracked (or one of the global strings) will be excluded. Regular expressions
+     * are also supported.
      *
      * @internal param string $this ->userAgent The user agent string.
      * @return bool
      */
-    protected function isUserAgentExcluded()
+    protected function isUserAgentExcluded(): bool
     {
         $excludedAgents = $this->getAttributes('excluded_user_agents', 'global_excluded_user_agents');
 
@@ -364,6 +365,10 @@ class VisitExcluded
                 if (stripos($this->userAgent, $excludedUserAgent) !== false) {
                     return true;
                 }
+                // if the string is a valid regex, and the user agent matches, this visit should be excluded
+                if (@preg_match($excludedUserAgent, null) !== false) {
+                    return preg_match($excludedUserAgent, $this->userAgent) ? true : false;
+                }
             }
         }