- define CIRCUITPY_BUILD_EXTENSIONS to predefined values
- set CIRCUITPY_BUILD_EXTENSIONS in port and board config
- reuse the support matrix "get_settings_from_makefile" to get it
- move the existing port and board specific values
- remove the C3 specific board values because it's not the default
- update build_release_files.py to use get_settings_from_makefile
Make them CIRCUITPY_FULL_BUILD = 0 and rework the boards to have
the same modules enabled (ish.)
Also make ZLIB require FULL_BUILD and disable advanced `micropython`
module APIs by default on all builds.
