[FLASK] Add extend-runtime endowment

[david0xd]

Explanation

This PR will add support for Snaps Platform endowment that provides extended runtime possibilities by controlling the execution timer.
In this PR added are:

• Endowment specification (label, description, icon) and its registration to permissions.
• New allowed event to the Snaps Controller Messenger configuration (ExecutionService:timerPauseRequest).

Related ticket following the work in Snaps repository: MetaMask/snaps#1604

Screenshots/Screencaps

Before

Nothing from before is affected by this PR.

After

TODO: Permission screenshot

Manual Testing Steps

Pre-merge author checklist

• I've clearly explained:
  • What problem this PR is solving
  • How this problem was solved
  • How reviewers can test my changes
• Sufficient automated test coverage has been added

Pre-merge reviewer checklist

• Manual testing (e.g. pull and build branch, run in browser, test code being changed)
• PR is linked to the appropriate GitHub issue
• IF this PR fixes a bug in the release milestone, add this PR to the release milestone

If further QA is required (e.g. new feature, complex testing steps, large refactor), add the Extension QA Board label.

In this case, a QA Engineer approval will be be required.

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[github-actions]

This PR has been automatically marked as stale because it has not had recent activity in the last 60 days. It will be closed in 14 days. Thank you for your contributions.

[github-actions]

This PR was closed because there has been no follow up activity in the last 14 days. Thank you for your contributions.