misc: Add package file for mip installation.

[sebromero]

This PR adds compatibility with the mip command (see here).
It's not clear to me if the cbor and senml packages are going to be hosted via the micropython-libs index. If so, the version specified in the dependencies may need to be adjusted accordingly.

[iabdalkader]

If this for installing the package on MicroPython, the dependencies should just be senml >= 0.1.0

[sebromero]

@iabdalkader I changed it. As far as I can see mip doesn't support semantic versioning so you have to pin an exact version. I didn't find any documentation on this but it seems to translate the dependency directly into a URL.

[sebromero]

I just ran a test with the new release of senml and it worked fine:

$ mpremote connect /dev/cu.usbmodem3871345733302 mip install github:sebromero/arduino-iot-cloud-py@mip-compatibility
Install github:sebromero/arduino-iot-cloud-py
Installing github:sebromero/arduino-iot-cloud-py/package.json to /flash/lib
Installing: /flash/lib/arduino_iot_cloud/__init__.py
Installing: /flash/lib/arduino_iot_cloud/ucloud.py
Installing: /flash/lib/arduino_iot_cloud/umqtt.py
Installing: /flash/lib/arduino_iot_cloud/ussl.py
Installing senml (0.1.0) from https://micropython.org/pi/v2 to /flash/lib
Installing: /flash/lib/cbor2/__init__.mpy
Installing: /flash/lib/cbor2/encoder.mpy
Installing: /flash/lib/cbor2/decoder.mpy
Installing: /flash/lib/senml/senml_pack.mpy 
Installing: /flash/lib/senml/__init__.mpy   
Installing: /flash/lib/senml/senml_record.mpy
Installing: /flash/lib/senml/senml_base.mpy
Installing: /flash/lib/senml/senml_unit.mpy
Done