feat: implement in-app automatic update downloader

[sameerasw]

This pull request introduces a comprehensive auto-update system for the app, including background update checks, user notifications, and streamlined update installation. It adds a new dependency for update management, integrates update logic into the UI, and introduces new services and receivers to handle update downloads and notifications.

Auto-update infrastructure:

• Added the AutoUpdater library dependency to manage update checks and installations. (app/build.gradle.kts)
• Introduced AppUpdateWorker for periodic background update checks, which notifies users if an update is available and updates cached state. (app/src/main/java/com/sameerasw/essentials/services/AppUpdateWorker.kt)
• Added DownloadUpdateReceiver to handle update download and installation requests via broadcast intents. (app/src/main/java/com/sameerasw/essentials/services/receivers/DownloadUpdateReceiver.kt, AndroidManifest.xml) [1] [2]

Update checking and notification logic:

• Enhanced UpdateRepository to use AutoUpdateManagerHelper for update checks, fallback to GitHub if needed, and improved error handling. (app/src/main/java/com/sameerasw/essentials/data/repository/UpdateRepository.kt) [1] [2] [3]
• Registered the REQUEST_INSTALL_PACKAGES permission for update installations. (app/src/main/java/com/sameerasw/essentials/domain/registry/PermissionRegistry.kt)

UI improvements for updates:

• Updated both MainActivity and SettingsActivity to display update status, show animated badges when updates are available, and provide a button to check for or install updates. (app/src/main/java/com/sameerasw/essentials/MainActivity.kt, app/src/main/java/com/sameerasw/essentials/SettingsActivity.kt) [1] [2] [3] [4] [5] [6] [7]

These changes together enable seamless update management, improve user experience around updates, and lay the groundwork for future enhancements to the app's update flow.