feat: Refactor app & account management UI code

[susnux]

Summary

1. Separate app store from account management
2. Split app and account management into better maintainable smaller pieces
   • Separate app content and app navigation component
   • Also split app store sidebar into own components for each tab.
   • The details tab now includes the same information like the sidebar on apps.nextcloud.com
3. Everything I needed to touch more then copy paste was refactored to TypeScript
4. Start using Pinia for the app store (currently only the navigation -> rest will be follow up)
5. Fix icon color broken in app-store #42998 by using inline icons for the app navigation
   • Use same icons on the app store navigation as used for apps.nextcloud.com that got a recent design overhaul.
   • Fix [Bug]: Icon of menu entry "Dashboard" in Apps section remains black in dark mode #42803

Screenshots

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)