This commit updates the `AnalyzerDependencyChecker` type to reflect the
recent changes to require all analyzers and dependencies to be
specified, and the changes in how we load analyzer assemblies.

Now that we require all analyzers and dependencies to be specified, we
no longer look next to the specified analyzers to optimistically locate
dependencies. Instead, we only consider the list of passed-in analyzers
*plus* the assemblies already loaded into the `AppDomain`. The latter
avoids unhelpful warnings in the event that the analyzer assembly
includes a code fix that take a dependency on a Visual Studio assembly,
which of course can't be included in the list of analyzers. We now
create a warning when we identify a missing dependency.

We now also check analyzers themselves for conflicts (i.e., assemblies
at different paths with the same identity but different contents)
instead of just their dependencies.

Fixes part of internal TFS bug #1167415.

We have reports of the BufferUndoState being unavailable in
UndoTemporaryEdits when inline rename has been dismissed due to an
external workspace change. This change prevents the crash by checking
for the existence of the relevant BufferUndoState while we await more
information on what leads to this state.

The RoslynPackage type originally lived in a seperate assembly than
Microsoft.VisualStudio.LanguageServices when it was important for us
to be able to support the core parts of Roslyn being installed atop
the existing Visual Studio 2013 language services. This is no longer
a supported scenario anywhere, so we should just get rid of the
assembly.

Doing this is easy, it's just a matter of moving the files and related
assets to the LanguageServices assembly. A MEF interface is added
to prevent a circularity around triggering a load of stuff in the
SolutionExplorerShim. That could be delt with later by moving the core
of that code back to LanguageServices, but I don't want to touch that
now since it's very sensitive.

Assert if we are not on the UI thread and give test authors the choice
to explicitly pass in the default namespace.

Attempting to generate a new file in an ASP.NET 5 web project would
deadlock because we were attempting to get the default namespace from a
worker thread.

The solution is to move the work of computing the default namespace from
ComputeOperationsAsync to GetOptions.  GetOptions is always guaranteed
to execute on the UI thread wheras ComputeOperationsAsync happens from a
worker thread.

This reverts commit 779cea70.

Attempting to generate a new file in an ASP.NET 5 web project would
deadlock because we were attempting to get the default namespace from a
worker thread.

The solution is to move the work of computing the default namespace from
ComputeOperationsAsync to GetOptions.  GetOptions is always guaranteed
to execute on the UI thread wheras ComputeOperationsAsync happens from a
worker thread.

This removes the majority of references to the deprecated Desktop
assemblies.  The only remaining ones are in the VSIX projects.  They
must remain until we actually delete the assemblies.

Fixes internal TFS bug #1128063

When NavigateTo is invoked on an IGraphNavigateToItem from the UI
thread, we are now careful to maintain control of the UI thread to
ensure any existing NewDocumentStateScope is preserved.

Fixes internal bug #1168460.

Fixes #1436

Fixes internal bug #1168460.

Fixes #1512

The solution explorer context menu that allows users to change severity of analyzer-reported diagnostics currently displays the following entries -
    Error
    Warning
    Info
    Hidden
    None

When the context menu is displayed, a check mark is displayed next to the entry representing the severity of diagnostic as configured in the project's ruleset file. This works fine in cases where a severity is explicitly specified for the diagnostic in the ruleset file.

However, in cases where the severity is not explicitly specified in the ruleset file, the diagnostic is assigned its 'default' severity and we don't display a check mark against any entry in the above menu. As noted in #1512, this is confusing because the 'default' severity is also one of the severities listed above.

This change introduces an additional entry named 'Default' in the above menu that will be checked in cases where the dagnostic does not have an explicitly specified severity in the ruleset file. If the user clicks this entry to change the severity of some diagnostic to 'Default', the entry corresponding to this diagnostic is removed from the ruleset file.

Update `AnalyzerFileReference` to take an `IAnalyzerAssemblyLoader`
instead of a `Func<string, Assembly>`.

track non roslyn text buffer changes as well as roslyn text buffer changes to delay solution crawler

There are 2 things incremental processor takes care of

@1 is making sure we delay processing any work until there is enough idle (ex, typing) in host.
@2 is managing cancellation and pending works.

we used to do #1 and #2 only for Roslyn files. and that is usually fine since most of time solution contains only roslyn files.

but for mixed solution (ex, Roslyn files + HTML + JS + CSS), #2 still makes sense but #1 doesn't. We want to pause any work while something is going on in other project types as well.

we need to make sure we play nice with neighbors as well.

now, we don't care where changes are coming from. if there is any change in host, we puase oursevles for a while.

Fixes internal TFS bug #1035934 "Undo didn't work in code file after
rename control's ID in properties"

Wrap the contents of ContainedLanguageCodeSupport,.TryRenameElement in a
global undo. This allows the undo of a rename done from the aspx
designer (for example) to correctly revert the C#/VB part of the rename
as well.

Fixes internal TFS bug 1043580.

When a codefix or refactoring throws an exception, we turn it off, log
it to the activity log, and put up and info bar telling the user what
happened.

With this change we also check to see if the codefix/refactoring was
implemented by the roslyn team and send a non-fatal watson report.

we will move away from IVsHierarchy and start to use ProjectIdGuid instead.

This ensures that the url displayed in the tooltip is more human readable.