This change implements version tracking the inputs and outputs of
generated code.
Version tracking is still best-effort - meaning that in some cases a
perfect system could avoid doing more work. However, since we base the
versions off of all of the inputs, we now that the guarantee that code
generation operations that happen 'out of order' will always result in
the newer inputs generating the newer outputs.
Fixes: https://github.com/aspnet/Razor/issues/2650
This builds support for tracking the effect of changes to imports on
other documents, and completes our model for being able to keep
generated code up to date.
The project snapshot now maintains a RazorProjectEngine as well as set
of Tag Helpers that are known for that snapshot.
Pivoted some more services to be snapshot-centric.
Also added the ability to track .cshtml documents to the project system.
For now most components just ignore document changes.
Ryan Nowak
Ryan Nowak