Add LogQL formatter

[gwdawson]

how to test this pr:

in grafana/lezer-logql:

1. checkout to this branch
2. build lezer from this branch

in grafana/grafana

1. checkout to the branch gareth/prettify-query
2. make sure you have enabled the feature flag lokiFormatQuery
3. add the following to package.json

   "resolutions": {
   "@grafana/lezer-logql": "portal:/path/to/your/repo/lezer-logql/dist"
   }

! grafana should now be using this build of lezer, try formatting some queries.

[matyax]

Before merging this I would:

• Add and setup Jest (we can do this together).
• Add the formatter tests.

[gwdawson]

@matyax besides the few bugs that are on the radar i believe this is ready so we can get an experimental version running in grafana 🙂