refactor!: migrate to KeyboardMode for layout modes

[albinpk]

Description

This PR introduces a breaking change by replacing the Map<String, List<KeyboardRow>> structure in KeyboardLayout with a new Map<String, KeyboardMode> format. This provides a more flexible and future-proof abstraction for defining layout modes, enabling advanced configurations per mode.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules