Cancel the signature help if the user navigates before it has been presented

Revert "Revert "Merge pull request #7510 from CyrusNajmabadi/analysisSpeedup""

Revert "Merge pull request #7510 from CyrusNajmabadi/analysisSpeedup"

This reverts commit 4ed5b596, reversing
changes made to 29ab8cba.

Ask Mode request: Fix IndexOutOfRangeException when running operation actions over Roslyn sources.

Fix vbc crashing when compiling 0 files into a library 

Ignore dlls that come from a 'packages' directory when searching for viable metadata references to search.

Fixes #8577

Clarify behavior when RunServerCompilation throws an exception

Reuse the SupersedeLowerVersions flag in the EE

Move interactive commands out of InteractiveFeatures

Disable Failing Documentation Tests (Stabilization)

Scripting scenarios set a special flag in the ReferenceManager to enable
additional tie-breaking rules in the presence of conflicting references.
Enable that same flag for the EE, which also routinely encounters
conflicting references.

Fixes internal bug 161294.

Match equivalent symbols in non-identical referenced assemblies

Handle VB property with type character when calculating trivia changes during EnC

Ignore dlls that come from a 'packages' directory when searching for viable metadata references to search.

A question was raised about the behavior of the compiler when RunServerCompilation throws an exception. After looking through the code I decided the approach most consistent with our existing code is:

1. Stop using `null` as a valid value in this API.  If the client determines it can't make the call use the Rejected coede.
2. Gracefully handle case where Task is faulted.  This puts the IO handling in a single place.
3. If the compilation could not complete on the server, for whatever reason, always fall back to local compilation.

closes #7866

Merge from master

made roslyn to use new GetContentLocation API from extension manager

added column filter to suppression column so that it doesnt count in …