Add simple script to fetch latest rust-analyzer

Pro:

 * No more wasted time and disk building it. Quite significant
   for my aging hardware

 * Server-side watching is awesome

Con:

 * Since chalk, working from a cargo workspace base directory
   risks killing my machine before the OOM-killer can do anything

I get over the unavoidable random death by never starting it from
the root of a workspace. I.e: so long as I open the project where
`Cargo.toml` is (instead of `Cargo.lock`), it's gold (or rather,
it hasn't crashed on me yet).

Id

b53bbf4c2bc32a83f1b8eb5309e28bdd45fe451c

Author

Caio

Commit time

2020-01-16T09:58:13+01:00