In 2f206670 I changed CodeModel to not open an editor when somebody
called GetStartPoint(), but it turns out that some paths of
GetStartPoint() internally called GetTabSize which assumed the text
was backed by a text buffer. This was the original reason the
EnsureEditor call was added, but I incorrectly determined that the
it was no longer needed. Now we just pass our OptionSet from the
document down and ask that, which will work in all cases.

Normally a given project will only show a single set of analyzer nodes, and finding those nodes and mapping to their underlying `AnalyzerReference`s is relatively easy.

When a project has multiple target frameworks, however, things get harder. Instead of a one-to-one mapping from projects in hierarchy to projects in the workspace, we have a one-to-many mapping: there will be one Roslyn project **per target framework** per hierarchy project. There are a few pieces to making this work properly:

1. When we have found a hierarchy item for an analyzer we already walk up the hierarchy to find the node for the project. We modify this to also look for the node representing the particular target frameworks (that is, with a "TargetNode" capability), if any, and extract the TargetFrameworkMoniker.

2. The `IHierarchyItemToProjectIdMap` has been updated to take that TargetFrameworkMoniker as an optional argument.

3. When checking the hierarchy associated with each Roslyn project we now extract and compare its TargetFrameworkMoniker, if desired.

Move helper API up as it will be using functionality in EditorFeatures as part of FAR refactoring work.

While investigating #17570, I discovered that we would sometimes create
"deferred" Roslyn projects for .NET Core projects that just hadn't been
asynchronously created yet. In *theory* that did no functional harm - they would
just get closed and converted to real projects when the project system created
the real project, but might as well not even bother creating them.

While I'm here, clean up PR feedback from #17335.

Also, update ProjectDisplayName to do what the docs say it does for Venus files.

Partially addresses #18382.

Reduce memory footprint of EnC TraceLog

This is something we could support one day, but until we do let's throw
a reasonable exception instead of exploding in some bizzare way.

Fixes https://github.com/dotnet/roslyn/issues/17782

This type follows the pattern that we assert in the finalizer that it
should have been cleaned up. If the type failed to initialize, we would
throw and crash the process even though the underlying failure is
already past at that point. I'm not saying we shouldn't crash there,
but that's a separate decision and we should then target the correct
place.

If a project being loaded in lightweight solution load references a CPS project
that does cross-targeting, we may crash trying to hook up P2P references,
because we were looking for a single project matching the project file name, and
language.  In the case of cross-targeting though, we create a project for each
TFM, and the .Single call would blow up.

To fix this, we now continue looking through projects until we find one with an
output path that matches our reference.

Fixes #17570.

renamed GetRemoteHostClientAsync to TryRemoteHostClientAsync to make it clear that it can return null when remote host is not available.

left GetRemotehostClientAsync there as Obsolete so that this doesnt break other team such as LUT.

will remove it once other team moved to new bits.