Fixes an issue with flow analysis where branches within `try` could be considered as going through `finally`

    We could incorrectly assume that variable is assigned (or unassigned in async capture tracking case).

    As a resutl we could
    - allow use of unassigned locals (undefined behavior)
    - not capture a local whose value survives `await` (NRE crash)

    Also added a regression test fro VB, which does not seem affected.

    Fixes:#19831

Test for #19609 that looks like have been fixed

Bug fixes for ref readonly

The fix is tecnhically breaking. Approved by compat council.

Merge master to post-dev15.5-contrib

Port change to remove IOperation feature flag from dev15.5.x to master

When dogfooding I ran into a few bugs in the Microsoft.NETCore.Compilers
package including

1. We need to oerride the CopyRefAssembly task
2. We need to surround the path components of the call with quotes

Do not invoke GetStandaloneNode helper in GetOperationWorker

Fixes #23004.
Fixes #23009.
Related to #22548 and #22229.

Generate an IVariableDeclaration instead of ILocalReference for loop …

Orchestrated build changes

Avoid showing language keywords after typing < in a doc comment

Unify IOperation APIs for while and do loops into a single IWhileLoop…

Generate parenthesized operation for parenthesized syntax in C#

Fix IArgument and IArrayInitializer to have null types

Fixes:#22858

This change is now just a test-only change that verifies the current behavior.

Merge master to post-dev15.5-contrib