Migrated subscriptions list screen to Compose (#163)

* Migrated subscriptions list screen to Compose

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Removed old menu functions

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Made methods private

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Migrated sync interval dialog to Compose

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Removed trailing colon

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Added content description

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Migrated subscriptions list screen to Compose

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Removed old menu functions

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Made methods private

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Migrated sync interval dialog to Compose

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Removed trailing colon

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Added content description

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Separate Settings from UI, provide LiveData

* SyncIntervalDialog: use MaterialAlertDialogBuilder

* [WIP] Add TODOs to replace Snackbar by UI elements; move logic to model

* Added `checkSyncSettings` to model

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Added more calls to `checkSyncSettings`

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Added permission explanation

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Added cards for permission requesting

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Fixed typo

Signed-off-by: Arnau Mora <arnyminerz@proton.me>

* Minor changes

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Signed-off-by: Arnau Mora <arnyminerz@proton.me>
Co-authored-by: Ricki Hirner <hirner@bitfire.at>