Android Auto: Retain queue after playback has completed. Swap icon position.

Description

This MR is a small change to two Android Auto issues: the playback queue and shuffle/repeat icon placement.

Motivation and Context

1. After the last track finishes the UI "collapses" with the disappearance of the queue and shuffle icons. Repeat is always shown even if the queue is empty, which seems a bit unexpected. The user can hit play to restart the audio playback from the first track, which results in the UI being immediately reconstituted with the re-appearance of the icons. While some of the icons should disappear (e.g. next, repeat, shuffle) they are on the right hand side of the screen, so it seems a bit more intuitive for those to update. The queue icon issue is more unexpected because it causes everything else to shift over. At some point, Google did suggest reserving space for the queue, but they have since revised their Build media apps for cars guidance to exclude the recommendation. It was also noted on various online forums the queue icon reservation did not work, so ultimately it appears to require a solution which avoids passing a null or empty queue entirely.

This change leaves the last queue visible on-screen, which enables users to select a track from the queue itself. This required logic changes to support re-loading the previous playlist and re-pointing to the desired track. Please review the addition of the playIndexOrLoadLastPlaylist method to determine if it is in the proper place, requires additional logic, should be combined with another method, etc.

2. Swap of the repeat and shuffle icons. The icons currently match the Android UI, with shuffle on the left and repeat on the right. I end up toggling shuffle on and off more frequently than repeat, which requires me to slide my hand to the left to hit the icon. After swapping the icons, I am able to depress the shuffle icon immediately after pushing the sub menu "..." button without sliding my hand over. It's a bit more ergonomic to use, albeit a tiny modification.

How Has This Been Tested?

Tested against an AA headunit and using the emulator

Screenshots / GIFs (if appropriate):

Current behavior:

During playback of last track. Repeat and shuffle are on the submenu:

Current repeat/shuffle menu. This change swaps the order of the icons.

New queue behavior after last track ended:

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Enhancement (non-breaking change which cleans up / improves existing functionality)

Checklist

• I have read the CONTRIBUTING section of the README document.