Better visualisation for chatops visual EXPLAIN
### Problem to solve
Even after visualising Postgres EXPLAIN in explain.depesz.com, it often isn't clear what could be done to speed up the query.
### Intended users
Software Developers and Data Analysts.
### Further details
Save time working out why a query is slow and what could be done about it, ultimately resulting in a faster cycle.
### Proposal
Integrate with pgMustard for users of `/chatops run explain --visual`.
### Permissions and Security
Same permissions as existing implementation.
### Documentation
Only small tweaks needed to the existing documentation page.
### Testing
The main risk is if some users are very familiar with explain.depesz.com and prefer it.
pgMustard already supports all modern browsers, but testing the --visual flag with the pgMustard integration will be needed.
### What does success look like, and how can we measure that?
Less time spent on each optimisation task, and a higher success rate (if those are measured).
### Links / references
https://www.pgmustard.com/
https://github.com/hairybreeches/pgMustard/issues/9
issue