Port to CircuitPython

[tannewt]

CircuitMatter currently targets CPython. It'll be much more useful on CircuitPython where hardware interfacing is easier.

Some things that may need to be changed in CircuitPython:

• Add/modify enum for CM support (or strip it from the library)
• Add mdns features for subtypes.
• Add cryptography for AESCCM.
• Add ecdsa. It may work as a pure Python library. It is used for elliptic curve computation.
• Add qrcode for displaying pairing info.