`CursorQueue` abstraction

In #12390, the batcher got refactored to work with cursors on queues of blocks, channels and frames. Since the cursor and queue are manipulated together and consistent state between the two should be maintained, we could add a `CursorQueue` abstract to keep the consistency by design.

_Originally posted by @sebastianst in https://github.com/ethereum-optimism/optimism/pull/12390#discussion_r1832546236_

> We may consider adding a `CursorQueue` abstraction that is a `Queue` with a cursor and then use it for blocks and frames. This way, we can better unit test the invariants between the queue and cursor.

Start by reading the batcher refactor in #12390, focusing on how cursors and queues are manipulated for blocks, channels, and frames. Identify the shared invariants, then assess how a CursorQueue abstraction could support unit tests for queue-cursor consistency and be used for blocks and frames.

Written by the indexing model from the issue text.