Fixes #540 "Stale rename entries in the lightbulb menu"

Prior to this change, dismissed rename tracking sessions continued to
provide codefixes which would silently fail when invoked, without
completing the rename operation.

With this change, we now do the following when rename tracking is
manually dismissed:

- Trigger the diagnostic service to reanalyze the document, thus
removing the rename tracking diagnostic.
- Stop providing a codefix when requested
- Show a dialog if a cached codefix is invoked explaining that the
rename was not performed.

Here are the there user scenarios:

1. The user dismisses rename tracking

    - The lightbulb will continue to show in the margin, regardless of
whether any codefix/refactoring is actually still available.

2. The user expands the lightbulb without it ever having been expanded
before.

    - In this case, we are queried for fixes and will not return any, so
either the lightbulb will disappear or it will contain other relevant
codefixes/refactorings at that position, excluding rename.

3. The user expands the lightbulb after it was previously expanded.

    - Our fix was already cached, so we can only give a reasonable message
when it is invoked.

Once #885 is fixed, we can instead implement IDiagnosticUpdateSource and
avoid forcing diagnostic reanalysis.