feat: add pause expiry in PauseController

[Thegaram]

Context: https://forum.l2beat.com/t/stage-1-requirements-update-security-council-walkaway-test/412

This PR changes PauseController in a way that enables permissionless unpause after the given timeout. This way, the chain operator or the Security Council minority cannot halt the chain indefinitely.

The basic flow is:

1. Operator pauses contract.
2. If the pause is legitimate, Security Council extends the pause expiry time.
3. A fix is implemented and deployed.
4. Unpause.
5. Security Council resets the pause cooldown period.

In the case of a malicious operator, the pause will expire automatically (no intervention by the Security Council is necessary), and t he cooldown period prevents the operator from pausing again.