[lib] Create an operation pruner

Summary:
We should prune the operations periodically because their number can keep growing. Frequency and max age were chosen arbitrary, and I'm not sure if they are good.

https://linear.app/comm/issue/ENG-8768/add-a-component-that-prunes-the-updates-periodically

Depends on D12949

Test Plan: Queued some operations for two different threads with different timestamps. Modified pruner constants and verified that correct operations were removed.

Reviewers: kamil, inka

Reviewed By: inka

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D12954