Ensure non-fatal exceptions are actually thrown

Revert "Merge pull request #18972 from CyrusNajmabadi/docHighlights2"

* Update versions

* Improve diagnostics

Do not even attempt to create indices for non-C#/VB projects.

This reverts commit 8262112e, reversing
changes made to 837ca214.

Order fields/properties better based on existing class structure.

Move DocumentHighlights (i.e. HighlightReferences) out of process.

Serialization kinds

Improve support for documentation comments in Replace Property with Methods

Add "Test" project type GUID to all test projects

Avoid calling GetDiagnostics on compilation during EnC analysis

Don't run naming rules on symbols with no name

Pool byte array used for reading from Stream during checksum calculation

Better handling of directive-trivia in UseExpressionBody/ReplacePropWithMethod.

Ensure linked files are kept in sync in the workspace

Notify XAML of renames caused by Naming Rule fixes

Remove forced unecessary asynchrony in flushing data to disk.

Fix building on 15.3

Generate better names for expressions used as parameters.

Avoid allocations due to use of Keys/Values instead of GetEnumerator

Offer enum completion inside an enum member's initializer

Eliminate delegate allocations in PooledObject.Create