Add uploader_id, uploader_name, and device_id for gmusicapi auth in gmusic plugin

[michaelmob]

gmusicapi auth uses the MAC address to "register" in Google's service. Running beet gmusic-upload will fail if you use beets on multiple machines because too many MAC addresses will be registered. The fix it to be able to use the same MAC address (and device_id for searching) for all of the machines.

uploader_id (optional)

Allow custom uploader_id to not reach maximum amount of registered devices. This field should be in the format of a MAC address.
From gmusicapi method docstring: Link

There are hard limits on how many upload devices can be registered; refer to `Google's
docs <http://support.google.com/googleplay/bin/answer.py?hl=en&answer=1230356>`__. There
have been limits on deauthorizing devices in the past, so it's smart not to register
more devices than necessary.

uploader_name (optional)

May not be necessary, but perhaps in the future.
From gmusicapi method docstring: Link

This doesn't appear to be a part of authentication at all.
Registering with (id, name = X, Y) and logging in with
(id, name = X, Z) works, and does not change the server-stored
uploader_name.

device_id (optional)

When running beet gmusic-songs from a different machine (with a different MAC address) sometimes you may get this error. The device_id is generated from the MAC address.

gmusicapi.exceptions.InvalidDeviceId: Invalid device_id XXXXXXXXA351.Your valid device IDs are:
* XXXXXXXXF92F
* XXXXXXXX43A5

You can then change device_id in your config to one of the valid device IDs that gmusicapi lists for you.

config example

plugins: gmusic

gmusic:
  email: musicgoogleaccount@gmail.com
  password: seekrit
  uploader_id: XX:XX:XX:XX:f7:97
  device_id: XXXXXXXX43A5

---

Let me know if this is acceptable and I will write something up for the gmusic docs.

[sampsyo]

Looks cool! And it looks like you've thoroughly investigated what these parameters are for. Can you please add them to the documentation for the plugin? Feel free to leave ones that don't have an obvious use (i.e., uploader_name) undocumented for now.

[michaelmob]

Okay, let me know if those additions are good.

[sampsyo]

Looks good! But I sort of like having the example first in the document—what do you think?

[sampsyo]

Hmm—I actually kind of liked having the configuration example up here, since people really will need to do this first. Any particular reason you moved it downward? Can we move it back here to stick with the logical flow of steps?

[michaelmob]

You got it!

[sampsyo]

A proper list of config options is great! Let’s definitely keep this stuff here.

[sampsyo]

Awesome. One last thing before we merge: could you please add a changelog entry to changelog.rst? Than we should be good to go!

[michaelmob]

🤙

[sampsyo]

Nicely done.