Split I2CDeviceDeinit out a bit

[brentru]

I2CDeviceDeinit is currently performing both an update and delete operation. This pull request adds I2CDeviceUpdateRequest to i2c.proto to allow for an update-only message.

The I2C modal should be able to send either an I2CDeviceUpdateRequest if a device's sensor has new time periods (from the modal) or if a device's sensor is disabled (also from the modal), or an I2CDeviceDeinitRequest to delete the i2c device itself.

I2CDeviceUpdateRequest sub-messages (AHTUpdateRequest, etc..) contain a period_ field , reflecting the return period of the modal.

[brentru]

@lorennorman Requesting a re-review of https://github.com/adafruit/Wippersnapper_Protobuf/pull/71/commits/9c45c4dc81f0e17c051854af3c4b28db917cda73

• Added shared sensorUpdateRequest sub-message
• Removed I2CDeviceType enum, this will be set in the device's I2C Driver instead.
  • Rationale for removal: Users shouldn't need to modify the protobuf to add a new I2C device driver.
• using enable_sensor = True as a way to enable the sensor, False to disable. Instead of two fields (enable, disable). Less unmarshalling and prasing on the device-side.
• Removes deprecated fields

[brentru]

@lorennorman Note that this reworks the structure of an I2CDeviceInitRequest message, the broker should be updated to support this PR.