Move subscriptions to database - Phase 1 (#105)

* Added Room and ksp

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Added type converter for `Uri`

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Added Room declarations

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Deprecated `CalendarCredentials`

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Generated Room schema

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Removed unused method

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Made `username` and `password` non-null

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Removed `put` method

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Removed account storage

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Added foreign key

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Made `lastModified` and `lastSync` nullable

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Removed migration method

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Moved `getProvider`

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Removed delete method to be moved somewhere else

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Removed `equals` and `hashCode` since `Subscription` is a `data class`

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Removed dao alias

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Renamed `get` to `getBySubscriptionId`

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Renamed `pop` to `remove`

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Removed `LIMIT` from query

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Removed extensions

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Moved Android functions to `DatabaseAndroidInterface`

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Updated database schema

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Credential: don't accept LiveData

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Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>
Co-authored-by: Ricki Hirner <hirner@bitfire.at>