Fixes #16334

Fixes
https://devdiv.visualstudio.com/DevDiv/_workitems?_a=edit&id=371205

Calling Wait() on a task means it will block the current thread until
    the underlying task is complete, however that task may still run on a
    background thread.  We are seeing an error where the async method is
    being scheduled to a background thread when we try and commit an edit to
    the buffer.  Edits to the buffer can only be made from the UI thread so
    exceptions are thrown.

    The simplest fix here is to not make the method async at all.

Fixes #15326, #15486

Temporarily marks data flow analysis over a region which contains local
functions as "failed." The current implementation is incorrect, so data
flow analysis should mark the result as bad rather than knowingly give
an incorrect result.

This change also causes extract method to emit a warning when extracting
over a region which involves local functions.

Fixes #15532, #16116, #8719, #8718, #8717

Related to #9960

Fixes #15345

Do not run Naming Styles on overrides or known explicit/implicit interface implementations.

The time spent trying to load .editorconfig files shows up in RPS, but this method does not actually use options that can be specified in .editorconfig.

It would be nice to move to System.Threading.Task.Dataflow however VS componentss we depend on depend on MS.Tpl.Dataflow.  Creates a bit of a packaging nightmare. They won't move to the roslyn alpha version because it's not pubilc.  Hence we need to use the standard one until this bug is fixed.

https://github.com/dotnet/corefx/issues/14869

* Make tuple types more round-trippable.

* Add more test info.

* Update test.

* Support roundtripping errors/non-errors.

Fixes #12182.

Related to https://github.com/dotnet/roslyn/issues/15225

Fixes #13249

Fixes https://github.com/dotnet/roslyn/issues/14492

Fixes #15804