[v0.2.0] Implement PendingActionExecutor (Sync Engine)

[Kavirubc]

Implement the logic loop to execute pending actions from simili-state branch after cooldown. Milestone: 0.1.0v

⛓️ Dependencies

• Depends on [v0.0.2] Implement PendingActionScheduler step #5 (PendingActionScheduler) to have data to execute.
• Depends on [v0.0.2] Implement GitHub API Client #4 (GitHub API Client) to perform actions.