Add scrubber to UVOL2

[CITIZENDOT]

Summary

• Adds read-only scrubber, which is enabled for both UVOL1 & UVOL2.
• Adds a read-only text, which shows the current track's manifest path.
  • Longest common prefix among the track paths is omitted for brevity.

References

closes #insert number here

QA Steps

[cla-bot]

Thank you for your pull request and welcome to our community. We could not parse the GitHub identity of the following contributors: David Gordon.
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