refactor(viewmodel): Generalize and streamline list building logic

This commit introduces a generic `buildList` function in `MainViewModel` to abstract the common logic for filtering, sorting, and building scroll maps for different data types.

Key changes:
- A new generic `buildList<T, R>` function handles common list processing tasks like filtering by hidden/pinned status, sorting, and generating sidebar scroll indexes.
- `getAppsList` and `getContactsList` are refactored to use this new `buildList` function, significantly reducing code duplication and improving clarity.
- List observation in `AppDrawerFragment` is simplified by introducing a local generic `observeList` helper function, reducing boilerplate for observing `LiveData` sources.
- App list loading now groups apps by profile type more efficiently and uses the new `buildList` function for final processing.

Author: CreativeCodeCat