Offload mode testing (blocked on media3 beta3 release)

[yschimke]

WHAT

Offload mode testing. Shows a SW/HW in TimeText to confirm whether offload is enabled.

WHY

Make testing offload easier without spelunking through logs to confirm.

HOW

Relies on a pending CL for ExoPlayer.

Checklist :clipboard:

• [ ] Add explicit visibility modifier and explicit return types for public declarations
• [ ] Run spotless check
• [ ] Run tests
• [ ] Update metalava's signature text files