Add support for out-of-tree userspace

[Erovia]

Description

Allow users to use out-of-tree keymaps/layouts.

Set the absolute path with qmk config user.userspace=/path/to/external/userspace and use qmk compile as usual.

TODO: Documentation

Opened as draft to get feedback and maybe help with writing the documentation.

Types of Changes

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

Issues Fixed or Closed by This PR

Checklist

• My code follows the code style of this project: C, Python
• 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.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[stale]

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 awaiting review, breaking_change, in progress, or on hold to prevent the issue from being re-flagged.

[coliss86]

@Erovia I'm highly interested in your PR, would you mind rebasing it against master please ?

[drashna]

Has some merge conflicts here.

[t-8ch]

Would it make sense to also document how to use this with plain make invocations?

[drashna]

I don't think so.

While it can be used with make, absolutely... the overall goal is to remove the dependency on make as much as possible, and push everyone to qmk.

Because of that, I don't think that adding documentation for make, well, makes any sense.

[t-8ch]

Ok!

[drashna]

Also, merge conflicts

[kbrock]

I really like the doctor refactor bit.
It is small, targeted, and makes the code easier to read.

Does it make sense to extract that into its own PR?
(not sure if the powers that be would agree)

[skullydazed]

I really like the doctor refactor bit.
It is small, targeted, and makes the code easier to read.

Does it make sense to extract that into its own PR?
(not sure if the powers that be would agree)

We actually refactored doctor.py pretty recently in #13298, it will land in master with the next develop merge.

[tzarc]

Has conflicts, removing the labels preventing stalebot from closing this automatically.
Suggest fixing things up to get it over the line.

[tzarc]

Converted to draft to prevent accidental merge.

[stale]

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 awaiting review, breaking_change, in progress, or on hold to prevent the issue from being re-flagged.

[stale]

Thank you for your contribution!
This pull request has been automatically closed because it has not had activity in the last 30 days. Please feel free to give a status update now, ping for review, or re-open when it's ready.