Optimize build workflow

[urob]

This PR contains two performance tweaks for the GHA build workflow:

1. Use treeless clones when pulling in dependencies. This reduces the download size from 1.7 GB to 610 MB.
2. Replace yaml2json | jq with yq. This saves the installation step shaving off a few more seconds.

The following table summarizes the performance impact for building a reviung41 with the stock config on ZMK v0.1.

	cold cache	warm cache	cache size
upstream	5m 28s	2m 02s	1.7 GB
treeless PR	3m 51s	1m 45s	610 MB

(See https://github.com/urob/zmk-build-benchmarks/actions for the benchmarks.)

Note

The dependency change is most impactful on cold caches. As Github caches expire after 7 days this should be a nice speed up for many build-user-config workflow runs.

For the upstream repo the gains are more limited since the cache should rarely be cold. On the other hand, there isn't really a downside since none of the workflows interacts with trees that aren't reachable from HEAD. For now I also applied the tweak to the ZMK build and test workflows but happy to revert that.

PR check-list

• Branch has a clean commit history
• Additional tests are included, if changing behaviors/core code that is testable.
• Proper Copyright + License headers added to applicable files (Generally, we stick to "The ZMK Contributors" for copyrights to help avoid churn when files get edited)
• Pre-commit used to check formatting of files, commit messages, etc.
• Includes any necessary documentation changes.

[urob]

As an aside, for local development using "blobless" clones gives most of the same performance gains without any of the performance penalties from interacting with trees that aren't reachable from HEAD.

To use them, simply replace west update with

west update --fetch-opt=--filter=blob:none

This reduces download size from 1.7 GB to around 800 MB.

[urob]

One more aside: The ZMK's west manifest pulls in a lot of dependencies that aren't needed for most builds. For example, most nice nano v2-based builds only require 4 modules:

- cmsis
- hal_nordic
- lvgl
- tinycrypt

Pulling in just those modules reduces build times on a cold cache from currently 5m 28s to 2m 11s!! Since most in-tree boards are nordic boards, this might be an argument to moving other boards to modules and specify those extra dependencies in the module manifest.

	cold cache	warm cache	cache size
upstream	5m 28s	2m 02s	1.7 GB
treeless PR	3m 51s	1m 45s	610 MB
minimal + treeless	2m 11s	1m 36s	240 MB