EnC: Implement support for editing types with primary constructors

[tmat]

Enables editing types with primary constructors and primary constructors themselves. Enables adding, deleting, renaming and changing types of parameters and switching from primary to non-primary constructor and vice versa.

Fixes various issues with editing record members and implements more unified approach that reduces special casing.

More work is needed to complete the experience and fix issues found during implementation.

Follow up issues:

• Primary constructor properties have sequence points but breakpoints can't be placed #63299
• EnC: Validate type layout constraints for types with primary constructors #68738
• EnC: changing parameter suppresses method body analysis #68708
• Rude edits not detected when changing (primary) constructor initializer #68731
• EnC analyzer does not register changes in a custom attribute with target #68458
• EnC: Changes in constructor signatures are not handled correctly #67268

[tmat]

    private bool HasInsertMatchingDelete(ISymbol newSymbol, Compilation oldCompilation, CancellationToken cancellationToken)

This might get simpler if we did two passes on the syntactic edits - first identifies what symbols need to be updated and the second can easily check for delete-insert pairs. Will explore that in a follow up.

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Refers to: src/Features/Core/Portable/EditAndContinue/AbstractEditAndContinueAnalyzer.cs:6650 in 9283d26. [](commit_id = 9283d26, deletion_comment = False)

[tmat]

@davidwengier PTAL
@phil-allen-msft FYI

[tmat]

@dotnet/roslyn-compiler PTAL at compiler tests.

[AlekseyTs]

Compiler tests LGTM (commit 8), with some comments for new test helpers.