`HistoryStorage` concept needs a "delete history" interface

[grigoryk]

Now that we're tracking history, we need to be able to also drop history. #1372 needs this for implementing a history expiration strategy. We'll also need this for user-triggered history deletion.

Shape of the API:

• history expiration is define either "volume" or "aggressiveness" or "time window" criteria
• user-triggered history deletion is going to be defined in terms of time - "today", "past week", "all".

┆Issue is synchronized with this Jira Task

[grigoryk]

Depends on mozilla/application-services#317 for places lib support so that we can implement this on browser-storage-sync.

[grigoryk]

A-S history deletion API meta: mozilla/application-services#621