Allowing idf components and User C Modules to be defined at the board level

[gentijo]

I have several build profiles that need the same base C code, but define which idf components are included as well as what User C Modules are used based on the profile selected where profiles are specified by the board name.

I have edited esp32/CMakeFiles.txt and usermod.cmake to implement this feature.
See PR, https://github.com/micropython/micropython/pull/14127/files

To see what an implementation would look like, see the board profiles here
https://github.com/gentijo/micropython/tree/rmp_micropython_modules/ports/esp32

and the selection of User C Modules here
https://github.com/gentijo/ROSMicroPy/tree/reorg-modules/modules

One thing that could be added to this PR is the ability to include the main directories for the boards to a directory outside of the Micropython code tree so there is not a ton of board definitions in the main Micropython directory