If the property is available, pipe it through in the same way that CPS does to the workspace for each project. This lights up features that check for this property in legacy projects that were wrong before. 

This enforces the use of `Assert.Null` or `Assert.NotNull`

* Revert "Revert "Make compilation outputs available via a workspace service (#34809)""

This reverts commit f4892bc4.

* Handle non-absolute path set by VB Web App IntelliSense project

This reverts commit 3bdbd560.

This reverts commit 3bdbd560.

This reverts commit 3bdbd560.

This produces a new free-threaded, well factored API for adding projects
to the VisualStudioWorkspace. The core type is the VisualStudioProject
which is a free-threaded API that you can use to push information over.
CSharpProjectShim, VisualBasicProject and CPSProject each have an
instance of VisualStudioProject that they push things through.

The inheritence model here is now smaller. CSharpProjectShim and
VisualBasicProject inherit from AbstractLegacyProject, but that's it.
CPSProject now inherits nothing, and AbstractProject is here purely
for TypeScript back-compat until they're moved onto the new APIs. The
expectation is F# and TypeScript both move to VisualStudioProject, which
we make public in some form. Then that type will go away.

* Add support for a new ProjectShimFactory to be consumed by CPS.

1. IProjectShim and IProjectShimFactory are the primary interfaces being introduced that CPS will use to forward project system changes to workspace hosts.
2. Refactored the UpdateOptions code in AbstractRoslynProject and sub-types so that it can be shared with the new project shim.

TODO: Add IVT to CPS binaries to enable consuming these APIs (need to follow up with DavKean)

* Add support for a new ProjectShimFactory to be consumed by CPS

1. IProjectShim and IProjectShimFactory are the primary interfaces being introduced that CPS will use to forward project system changes to workspace hosts.

2. Refactored the UpdateOptions code in AbstractRoslynProject and sub-types so that it can be shared with the new project shim.

3. Add IVT to CPS projects to enable consuming these APIs.

* Fix tests

* Add tests for new CPS project shim.

* Fix the tests and update the Shim factory API to take CommandLineArguments.

* Fix VSI test - VB compilation options must also contain latest parse options

* Some more code refactoring to ensure that for the CPS shim we avoid getting properties through the hierarchy while creating the shim and adding new source files.

* Some more code refactoring to address review feedback:

1. Rename IProjectShim and IProjectShimFactory to IProjectContext and IProjectContextFactory respectively.
2. Add a new sub-type of AbstractProject, namely "AbstractLegacyProject", for legacy C# and VB project system shims. All the Hierarchy accesses for computing properties have been moved to this sub-type.
3. Move legacy project system specific interface implementations (IVsHierarchyEvents, IIntellisenseBuildTarget and ICompilerOptionsHostObject) to AbstractLegacyProject.
4. Merge AbstractRoslynProject into AbstractProject - the only addition in AbstractRoslynProject seem to be support for VsENCRebuildableProjectImpl, which was anyways an optional field.

* Change the name of the flag taken by AddSourceFile to "isInCurrentContext"

* Address review feedback

* Fix tests broken by last commit

* Further cleanup of options setting infrastructure

* Minor refactoring of the Options setting APIs

These tests were all using WpfFact, but not actually doing anything
that required either WPF or an STA thread. We plan to enable
parallelization of Facts (but not WpfFacts), and this ensures we can
parallelize as many tests as possible.