Gathering LSP declarations in zeta_cli can take a really long time for
big repos and has to be started from scratch if interrupted.
Instead of writing the cache file once we have walked the whole
worktree, we'll now do so incrementally as we complete each file. On
subsequent runs, we'll load as many valid declarations as has been
previously written to the cache, and then continue to request the rest
from the LSP which will append to the existing file as it makes
progress. If the last cache entry is incomplete, we'll truncate the
cache file to the end of the last valid line and continue from there, so
we can just `ctrl-c` without breaking resumability.
Release Notes:
- N/A
Agus Zubiaga
a693d44553