framework/13-inch: fix enhanced audio device priority

[Stebalien]

Description of changes

On framework laptops, ensure that the "enhanced audio" sink for the laptop speakers has a lower priority than bluetooth speakers (by giving it the same priority as the built-in laptop speakers, 1009). Bluetooth speakers have a priority of 1010 by default.

NOTE: the existing comment in the code claiming that higher values mean lower priority is incorrect; lower priorities values mean lower priority.

Things done

• Tested the changes in your own NixOS Configuration
• Tested the changes end-to-end by using your fork of nixos-hardware and
  importing it via <nixos-hardware> or Flake input

After testing, my audio switches from my laptop speakers to my bluetooth headphones when I connect them.

[JohnAZoidberg]

How did you figure out the numbers?

[Stebalien]

1. wpctl status to get the devices.
2. wpctl inspect DEV_NUM to get the properties.

Then I grepped around in the wireplumber source code and found where the priorities were configured (see the links in the PR description). The bluez priority is always 1010 for sinks and 2010 for sources. The calculation for built-in audio devices is trickier, but it looks like it should be a stable 1009 for Framework laptops, assuming it always shows up as the "first" device.