feat: Use biome to parse turbo.json (#6810)
### Description
Uses biome to parse our turbo.json files. Specifically it uses
`biome_deserialize` instead of serde, which allows us to attach span
info. The PR converts the env variable prefix error as a proof of
concept, but of course, more errors can be converted down the line.
Also factors out turbo.json into a separate module since it's a little
different than the rest of config.
### Testing Instructions
We have fairly good testing for turbo.json parsing already. I added a
test for the env var prefix error.
Closes TURBO-1946
