* add ActiveLeavesUpdate, remove StartWork, StopWork
* replace StartWork, StopWork in subsystem crate tests
* mechanically update OverseerSignal in other modules
* convert overseer to take advantage of new multi-hash update abilities
Note: this does not yet convert the tests; some of the tests now freeze:
test tests::overseer_start_stop_works ... test tests::overseer_start_stop_works has been running for over 60 seconds
test tests::overseer_finalize_works ... test tests::overseer_finalize_works has been running for over 60 seconds
* fix broken overseer tests
* manually impl PartialEq for ActiveLeavesUpdate, rm trait Equivalent
This cleans up the code a bit and makes it easier in the future to
do the right thing when comparing ALUs.
* use target in all network bridge logging
* reduce spamming of and