MLX90393 three-axis magnetometer

[functionpointer]

What does this implement/fix?

Adds support for the melexis MLX90393 magnetometer.
This integration does use an external library, but the library is designed with an abstraction layer for i2c.
This means it does not depend on Wire and uses esphome's i2c abstraction instead.
As a result, this integration should work just fine with multiple i2c buses and on esp-idf.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Other

Related issue or feature (if applicable): fixes

Pull request in esphome-docs with documentation (if applicable): esphome/esphome-docs#1641

Test Environment

• ESP32
• ESP32 IDF
• ESP8266

Example entry for config.yaml:

# Example config.yaml
sensor:
  - platform: mlx90393
    oversampling: 1
    filter: 0
    gain: "3X"
    x-axis:
      name: "mlxxaxis"
    y-axis:
      name: "mlxyaxis"
    z-axis:
      name: "mlxzaxis"
    temperature:
      name: "mlxtemp"

Checklist:

• The code change is tested and works locally.
• Tests have been added to verify that the new code works (under tests/ folder).

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in esphome-docs.

[probot-esphome]

Hey there @functionpointer,
Thanks for submitting this pull request! Can you add yourself as a codeowner for this integration? This way we can notify you if a bug report for this integration is reported.
In __init__.py of the integration, please add:

CODEOWNERS = ["@functionpointer"]

And run script/build_codeowners.py

_{^{(message by NeedsCodeownersLabel)}}

[functionpointer]

Should i make a 1.0.0 release for the library functionpointer/arduino-MLX90393 ?

[jesserockz]

Should i make a 1.0.0 release for the library functionpointer/arduino-MLX90393 ?

Up to you =)

[functionpointer]

Merge conflict solved.