adds support for dongles

[RasmusKoit]

Currently there is a code check for splitting firmware into left and right halves, this code change implements also splitting by _dongle or _central suffix

[RasmusKoit]

Ran a test run with https://github.com/RasmusKoit/miryoku_zmk/actions/runs/10227455196/job/28298921969 for just _left and _right halves

Here is a test run with the same changes + outboard containing a dongle https://github.com/RasmusKoit/miryoku_zmk/actions/runs/10221908453

[RasmusKoit]

i am also in the process of writing docs for dongles in the zmk repo here

[manna-harbour]

Thanks for the PR!

The suffix names aren't explicitly mentioned in your docs, but the examples use only dongle. Is central just an alternative to that? I guess for ZMK all of the suffix names are just convention, and they can actually be anything.

The workflow requires a list though. Perhaps just one name should be encouraged in the docs (as it is now) and supported in the workflow, for simplicity.

[RasmusKoit]

will rework it to use central 👍

[manna-harbour]

Is central preferred over dongle? Is there a convention yet?