added Language property to ParseOption and CompilationOption

Fixed null exception for solution which has both C#/VB and typescript/javascript

Print out more information about why a test failed.

property name followed the compiler code base pattern.

Provide user facing options to control if expression bodied members are preferred or not.

Rollback any document changes if adding a nuget package fails.

track session across remote host

Enables CreateTupleTypeSymbol_UnderlyingTypeIsError test for VB

guard session against ObjectDisposedException from StreamJsonRpc.

Fixes: #13277

Move to TaskCompletionSource in AsyncLazy now that we're no longer on .net 4.5

Fixes #7505