(src/coreclr/src becomes src/coreclr) (#44973)
* Move src/coreclr/src/Directory.Build.targets to src/coreclr
Merge src/coreclr/src/CMakeLists.txt into src/coreclr/CMakeLists.txt
* Mechanical move of src/coreclr/src to src/coreclr
* Scripts adjustments to reflect the changed paths