i15-1: "Add all to queue" button should just add all to queue

Currently "Add all to queue" selects all items and adds them to the queue.
It should not need to select them first, just add all that are available to the queue.

Ideally
1. Status should changed to "Queued" upon addition
2. Notification snackbar to show "X items have been added to the queue".

~Question - Should it only add the ones that are not added yet, rather than adding again ones that are already queued?
In effect, that if you want to add the same item again, it should be done manually~ This has been added in #112

Locate the "Add all to queue" button and the code that currently selects items before adding them. Verify that available items are queued directly, their status changes to "Queued," and the snackbar reports the number added; the duplicate-item behavior is addressed in issue #112.

Written by the indexing model from the issue text.