Should constant values be included in stub files

[Josverl]

Pro:

• can be useful to help understand the interface

Con:

• against recommendation, against PEP , slows down linters , type checkers
• no tooling support ( all stubbers remove the values)

requested by @brianreinhold in https://github.com/orgs/micropython/discussions/13527

• firmware stubber to capture both types and values in .pyi files.
  This eliminates a mypy.stubgen step - which removes all values
• avoid overwriting value from frozen modules - need to merge rather than overwrite with frozen modules.
  There is a risk that this will obscure some classes or values that cannot be detected run-time
• avoid needing to run mypy.stubgen in other steps,
  • or compensate for that by re-merging lost but relevant information in a 2nd step