Switch the activity filter to use the new session-based API that
deliver incremental updates to the current filter.
Drop the old quick win listening for individual change events and
use the unified API instead.
The new transactions (on-top) trigger the old "new transactions" buttons
that trigger reset of the current filter and the top new transacitons
highlighted.
Highlight mixed changes (not new on top) as they come in
Highlight new changes on filter reset
Closes#12120
Stefan