Add Keychron C1 Pro V2

[adophoxia]

Description

As title. This version of the C1 Pro uses an STM32F402 (Chinese variant of the STM32F401, but is similar enough to where it'll work fine with being defined as an STM32F401), so as to not be confused with the v1, using an STM32L432, hence the v2 nomenclature. Codebase will be similar to that of the C3 Pro from #24874, so unless anything, feedback would be appreciated. PR for the C2 Pro V2 will be made as well be in "sync".

Types of Changes

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

Issues Fixed or Closed by This PR

• N/A

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).