* add regression test for buffered source resolver

* change assert

made checksum builder to resilient to missing data such as compilation/parse options which some projects such as typescript don't have.

also made creating solution to only include project type workspace knows about to create.

some of these will change once checksum moves into solution state itself, but the concept of having Null data will remain to support projects that don't have all data or filtering out projects that workspace doesn't know how to craete.

(thank you @keyboardDrummer!)

The important part is that we don't create these services until they are needed.
We don't need complicated logic about later on disabling them.  The current logic
attempts to disable them when the same packages that loaded them, get unloaded.
But packages only get unloaded when VS is shutting down. And we don't need to
do complex work in that case as our entire environment is going away.

--

In other words, we had complexity around returning teh service to an 'unstarted'
state just so it could be started up later.  But it will never be the case that
we'll ever start the service up again as the only reason we moved it to 'unstarted'
was because VS was shutting down.

Make the logging service async.  That way we can move package update out of proc while still logginc to the VS log in a non-blocking fashion.

* Update facades in VSIXes

* Add System.IO.Compression to the signing list