Factor out CompilerAssert, TestFramework, ILChecker and Utilities (#9350)

* [WIP] Factor out CompilerAsserts, TestFramework, ILChecker to separate library

* [WIP] +NUnit reference; Put Utilities.fs under module

* Fixed tests to use new helpers library

* Added <NoWarn>3186</NoWarn> to the FSharpSuite.Tests.

* Added missing import for the TestHelpers.

* Added missing solution entries for the project

* Fix tests.fs to run tests with proper path

* Fixed more paths in the tests

* More fixes to test paths

* More fixes to test paths (again)

Author: vzarytovskii