feat(developer): support building .keyboard_info without source version

Relates to #9351.

Adds support for building a .keyboard_info file without having source
.keyboard_info file:

* Constructs a default source .keyboard_info in memory
* Hints if license is missing
* If LICENSE.md is present, verifies it matches the MIT license text
* Adds project option to turn on or off metadata generation. This will
  default to False for version 1.0 projects, and to True for version 2.0
  projects. This means that the keyboard repository will need a PR to
  enable metadata generation for existing projects in the repository,
  but this is important to avoid breaking builds for existing projects
  that are not in the repository.
* Turns on additional c8 coverage for kmc projects