DRAFT PR: 1470 escape hatch add sliding windows to light client contract

[alysiahuggins]

Closes #1470 TODO

• a check for a block number that's too small? e.g before/when the genesis block was/is recorded?
• should there be a calculation from numUpdates since firstupdate to determine if hotshot was live?

This PR:

• delayThreshold variable
• updateDelayThreshold function
• isHotshotLive function

This PR does not:

• WIP

Key places to review:

• isHotshotLive function

How to test this PR:

forge test --match-contract LightClient_delayThresholdTest -vvv --ffi

Things tested

• isHotshotLive functionality
• l1BlocksUpdates is updated when the newFinalizedState function is successfully called
• updateDelayThreshold function