rMOZILLABETA3e4fdf53c557

Bug 1625935 - [devtools] Implement ResourceWatcher with legacy listeners for Storage panel r=ochameau

This is D86050, rebased on top of current central. I kept it a separate commit, so the new stuff can be reviewed separately in a different revision.

Differential Revision: https://phabricator.services.mozilla.com/D91122