Feature Request: Add additional stats/metrics for VDiff

[mattlord]

Feature Description

We setup vdiffStats in #14786 . We should utilize that to add some additional stats / metrics that can be helpful in debugging and understanding what's happening in the system. Some basic ideas to start with:

• Count of VDiff errors
• Count of VDiff errors by UUID
• Errors by VDiff UUID
• Count of actions (Create/Stop/Resume/Show/etc)
• Count of actions (Create/Stop/Resume/Show/etc) by VDiff UUID
• VDiff start and end times by UUID
• VDiff diff table initialization (synching up streams and preparing consistent snapshots for the diff) times by UUID
• Any of these things by vreplication workflow
• ...

Use Case(s)

Observing, understanding, and debugging Vitess behavior in production when doing VDiffs.