These tests run in parallel on CI machines, which can delay execution of
asynchronous operations for long periods of time. Increase test timeouts
to reduce the number of cases where tests fail.

* Minor cleanup of some ObjectFormatterTests

* Unskip test

It's possible to have a batch remove and re-add a project reference
to the same project, even if you're removing different reference paths.
If that happened, we'd try to add the duplicate reference first which
would crash.

Fixes https://github.com/dotnet/roslyn/issues/39032
Fixes https://github.com/dotnet/roslyn/issues/43632

These should only get called as a part of a larger operation that is
already holding the lock; we can assert that directly and then remove
the extra lock statements.

Now that we have a work around for the VB runtime reference issue when
using the embedded option we can move MS.CA.VisualBasic to be
multi-targeted to `netcoreapp3.1` and `netstandard2.0` just as we do
for MS.CA.CSharp

Related: https://github.com/dotnet/sdk/issues/10591

Fixes #43828

https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1070469

Fixes #43812
My prior Options related code refactoring causes certain CodeStyle option updates in the CodeStyle Tools Options page to not get saved properly. As a result, updating these options in this page has no effect and user is forced to workaround by manually updating/creating an editorconfig file.
The core issue is that `SetOptionAndUpdatePreview<T>` method is invoked in two different ways for CodeStyle options:
1. 'T value' argument is the new underlying bool/enum CodeStyle value to set.
1. 'T value' argument is the new CodeStyle option wrapping the new underlying bool/enum + notification preference to set.

We were only handling the first case, and the second one silently throws a cast exception, rendering the option set having no effect. Now we handle both cases. I have manually verified that updating all the CodeStyle Options on the page and closing/re-opening the page has changed values.

We are also doing couple of follow-up items to guard against such regressions in future:
1. Adding the verification of CodeStyle options page scenarios to our internal manual test pass scenario list. These will be manually verified prior to each release.
2. #43813: Investigate writing an integration test for Tools Options CodeStyle page

* Move RazorRemoteHostClient functionality to ExternalAccess.Razor

* Add file

Sometimes we do want the preview/provisional tab to receive focus. For example, when navigating to definition of a symbol and there's only one definition.

Fixes #43585

This reverts commit 146f9208.