data driven split serial implementation

[evils]

Description

basically the remaining changes of #17959 after a year of keeping my local changes in sync

these are my local changes i needed to get a pi pico based handwired tbk mini working

Types of Changes

• [ ] Core
• [ ] Bugfix
• [ ] New feature
• [x] Enhancement/optimization
• [ ] Keyboard (addition or update)
• [ ] Keymap/layout/userspace (addition or update)
• [ ] Documentation

Issues Fixed or Closed by This PR

• none i could find

Checklist

• [ ] My code follows the code style of this project: C, Python
• [x] I have read the PR Checklist document and have made the appropriate changes.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [x] I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[evils]

didn't see that the change of PR base resulted in a merge conflict i've resolved that

if i understood #22829 correctly, define flags that don't need a true / false value but just need to exist or not, should be of type flag in info_config.hjson

[github-actions[bot]]

Thank you for your contribution! This pull request has been automatically marked as stale because it has not had activity in the last 45 days. It will be closed in 30 days if no further activity occurs. Please feel free to give a status update now, or re-open when it's ready. For maintainers: Please label with bug, awaiting review, breaking_change, in progress, or on hold to prevent the issue from being re-flagged.

[evils]

this PR's not stale, i intend to keep it mergible though it is waiting for the json interface to be solidified more formally which may make this work obsolete

and i have no idea what the CI failure is due to