UI and animation improvements for the audio player

Description

Minor Ui / behavior improvements for the audio player:

• Advanced options and bars are now opaque
• Mini player progressbar and icons animations now follow the scroll instead of being shown when state changes
• Fix an UI bug where a 2dp line was shown on top of top bar

Also:

• Fixes the unit issue
• Refactor to delegate for au the AudioPlayer animations

Motivation and Context

How Has This Been Tested?

Screenshots / GIFs (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Enhancement (non-breaking change which cleans up / improves existing functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

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

Resolves

Fixes: # Mention: #