In this commit the logging system was re-worked
dfa4d94827 fs: Remove github.com/sirupsen/logrus and replace with log/slog
Unfortunately the systemd logging was still using the plain log
package and this caused a deadlock as it was recursively calling the
logging package.
The fix was to use the dedicated systemd journal logging routines in
the process removing a TODO!
This removes logrus which is not developed any more and replaces it
with the new log/slog from the Go standard library.
It implements its own slog Handler which is backwards compatible with
all of rclone's previous logging modes.
