Add keyboard QK65 R2

[Siilwyn]

Description

Add Qwertykey's keyboard the QK65 round 2.
I've based this on Owllab's fork.
The default layout is a copy of the default 65_ansi_blocker keymap with less second layer keys.

Types of Changes

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

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).

Notes

Succession of this previous PR: #21896
Qwertykeys shared the bootloader code with me and with the help of people on discord we figured out this custom stm32duino bootloader has a hardcoded bootloader key with not way to activate bootmagic: So I clarified this in the readme.

tri mode wireless

[drashna]

This appears to be a tri mode wireless keyboard:
https://www.qwertykeys.com/products/qk65-v2

See #24085 for details on this issue.

[sigprof]

The names of Qwertykeys boards are somewhat confusing — QK65 v2 is a different board from QK65 R2, and there were some wired-only PCB options for QK65 R2 (for some reason https://www.qwertykeys.com/products/qk65-parts-1 currently does not list the QK65 R2 ANSI Hotswap PCB which should match this firmware, but maybe they just don't have any extras available).

[Siilwyn]

Yes sadly extras and other parts of the QK65 R2 have not been available for some time, I don't think they'll ever make any as they said it's a discontinued product, they don't work with the manufacturer anymore. But correct this is not the QK65 v2, besides qwertykeys have provided the source for this board so #24085 is not applicable here for the wired variant.
Please reconsider, I've put a lot of time in this PR and this is an old board that's not sold anymore. I understand if you want to put future qwertykeys products on hold.

[Siilwyn]

@drashna I can adjust the readme to clarify this is about the wired QK65 R2, thoughts?