Revived rules are not properly displayed in the rule history

[xichen2020]

Currently if a rule is revived after it's deleted, it is unclear from the UI that the rule has been deleted and revived. In particular, the deletion of a rule is not clearly marked in the UI, which may cause user confusion.

We should enhance the UI so that a rule deletion is clearly shown in the UI (e.g., add a Tombstoned column or something along those lines). The backend already passes in a Tombstoned flag for the rule deletion operator, which frontend can use to identify rule deletions.