The new Lake build monitor is now more selective, accurate, and prettier
in what it prints.
**Key Changes:**
* Poll jobs at a fixed frequency (100ms), updating the caption and
finished job count.
* Add `action` field to jobs to record information about what jobs do.
It enables distinguishing between jobs which build something, fetch from
a store, or reload logs from the cache.
* At standard verbosity, print build captions only when a job is know to
build or fetch something (i.e., `action >= .fetch`).
* Add an icon and color to job captions based on their log-level / build
status. Also add color to levels in logs.
* Add `--ansi`/`--no-ansi` to toggle Lake's use of ANSI escape codes.
* Fix some `v4.8.0-rc1` bugs and `--old`.
Closes#2822.
7648bf255c