Keep a trace of compiled files

[tgodzik]

A lot of the time it's difficult to debug transient compilation failures and it might be too much too flood the user's log with Zinc output. In those cases it might be good to keep a separeta .bloop/compilation.trace.json similar to metals trace files.

We could keep there a more concise information:

1. What files are being compiled
2. What diagnostics were produced based on that compilation
3. Which artefacts were copied where
4. When noop compilation was done instead of invoking zinc.

This could be enabled by a setting options from Metals.