Fixes #466 "Use a 'TriggerDiagnosticDescriptor' for the rename tracking
diagnostic"

Updates the RenameTrackingDiagnosticAnalyzer to use a
TriggerDiagnosticDescriptor, which prevents the diagnostic title from
appearing in the preview area of the lightbulb. We now pass the
RenameFrom and RenameTo names as part of the Diagnostic's property bag
and construct the localized codefix title based on these in the codefix
itself.

Fix #554: This fixes a crash that was caused by invoking a lightbulb
item that caused an Inline Rename session to launch when there's already
an inline rename session active. We now check for inline rename sessions
during lightbulb commit. If an inline rename session is active, we halt
the lightbulb commit and tell the user to complete their rename session.

This only prevents one (but probably the most frequent) manifestation of
a larger problem in which rename is trying to perform a series of
changes to the workspace that can be interrupted by some other feature
applying its changes to the workspace. This larger design problem is
tracked as #681.