Add temperature units to MQTT Climate

[panctronic]

Description:

Modifies the MQTT climate component to support auto-discovered MQTT Climate devices configuring which temperature unit they use. This allows a HVAC unit that internally operates in Celsius to work with a HA installation with a Fahrenheit unit configuration.

Related issue (if applicable): fixes #30600

Pull request with documentation for home-assistant.io (if applicable): home-assistant/home-assistant.io#11684

Example entry for configuration.yaml (if applicable):

n/a

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist

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

• Documentation added/updated in home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly. Update and include derived files by running python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

If the code does not interact with devices:

• [ x Tests have been added to verify that the new code works.

[homeassistant]

Hi @panctronic,

It seems you haven't yet signed a CLA. Please do so here.

Once you do that we will be able to review and accept this pull request.

Thanks!

[probot-home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as its been labeled with a integration (mqtt) you are listed as a codeowner for? Thanks!

[balloob]

Please add it to the PLATFORM_SCHEMA and add tests.