Implement Required Members for VB (#66084)

* Add and implement IPropertySymbol.IsRequired and IFieldSymbol.IsRequired.

* Add and implement NamedTypeSymbol.AllRequiredMembers.

* Implement MethodSymbol.HasSetsRequiredMembers

* Implement checking required members in constructors, sketch out test methods.

* Implement remaining errors:

* Block inheriting from types with required members
* Block calling constructors with invalid required member lists
* Block substituting types with required members in As New, unless the parameterless ctor has SetsRequiredMembers.

* Fill out all tests

* PR feedback

* PR feedback#

* PR Feedback

* Compile errors, missed feedback item.

* Fix compile errors, add a few more tests.

* Addressed a number of PR feedback comments. Lots of new tests, fixed a few revealed bugs, handle Nothing converted to a struct with required members.

* PR feedback

* Remove Nothing handling to align with C#.
* Remove suppressions of cascading errors.
* Expand unbound test coverage.
* Expand tuple test coverage.

* Pass correct containing type in local rewriting of tuples.

* Fix test baseline

* Simplify EnsureRequiredMembersCalcuated.

* Add additional test verification.

* Remove unnecessary imports

* Tighten retargeting asserts and add a test

* Fix C# equivalent code.

docs/compilers/Visual Basic/Compiler Breaking Changes - DotNet 7.md

@@ -0,0 +1,8 @@
+# This document lists known breaking changes in Roslyn after .NET 6 all the way to .NET 7.
+
+## `RequiredMembersAttribute` cannot be manually applied
+
+**Introduced in VS 17.6**
+
+As part of implementing VB support for consuming `required` APIs, it is now an error to manually apply `RequiredMembersAttribute` in
+source. VB will now correctly interpret these attributes in metadata and allow instanciating types with required members.