The intent of CONTRIBUTING.md is to provide guidelines for contributing to a
repository.  Ours was a mix of guidelines, best practices and developer
workflow.  The other aspects are already covered in our other contributing
documents.

Changing CONTRIBUTING.md to be guideline focused.

Without this, we always end up publishing the debug version of the
compiler.

fixed crash on TS due to missing designer attribute service on OOP

Filter projects based on language name

Regression test for #19434 which appear to be fixed.

	Respect user settings around 'Blocks' when adding parameter null checks.

Made OOP to handle initial solution case better and made it to have better perf.

Be resilient to documents/projects with null-filepaths in our persistence layer.

Do not pass around null SymbolTreeIndices.  Instead, pass around empty ones.

Avoids [VSO bug 433873](https://devdiv.visualstudio.com/DefaultCollection/DevDiv/_workitems/edit/433873).

When mapping an `IVsHierarchy` to the related Roslyn project we end up asking each project for its associated `IVsHierarchy` and checking if various properties match up with those on the "origin" hierarchy. The properties supported and the interpretation of their values varies from one project system to another. The `HierarchyItemToProjectIdMap` class was implemented when Roslyn only supported C# and VB projects, and was designed with those in mind. Now that TypeScript can also have Roslyn projects we need to filter out everything that isn't C# or VB or we risk asking for properties that aren't supported or possibly misinterpret the values.

Merge Features/async main

tests only. no ask mode approval is required. thanks!

Closes:#19434

Use-throw-expression should not be offered when the 'if-block' has additional statements in it

Pool the simplifiers we use when simplifying code.

Preserve trivia when converting a numeric literal base

* remove remaining prototype comments, add extension method tests

* fix old test, address review feedback

* ReturnType implemented on each subclass

* added more tests on non-async task returning mains

* add obsolete tests

* autoformat

* add better tests for successful task overrides