Backport 8174 (symbol-based custom inspection methods)
Backport #8189 (because the rest depends on that) and #8174, with one require() line added that is present in master but missing in v6.x.
/cc @Fishrock123
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Backport #8189 (because the rest depends on that) and #8174, with one require() line added that is present in master but missing in v6.x.
/cc @Fishrock123