The error reporting here was all truncated to "cancelled" or "timeout"
with no extra information, resulting in opaque errors like "internal
errror" with no other information.  This changes a number of functions
over to anyhow::Error with cause chainging.  Only top-level timeouts
are still propagated as SymbolicationError::Timeout with some inner
onces being mapped to anyhow::Error, which now maps into
SymbolicationError::Canceled.

Error reporting in the request future now also logs the error instead
of only capturing it in Sentry.  This allows also getting the errors
during test runs and other debugging.

This only wraps inner errors.

This was only saved for things which aren't a timeout.  Let's not
change this now.