Add state_translated function to jinja templates

[PiotrMachowski]

Proposed change

This pull requests adds possibility to translate entity's state in jinja templates. This feature makes it much easier for users to send notifications including entities' states (e.g. weather status), use TTS, present data in markdown cards and probably much more.

code:

{{ states("sun.sun") }}
{{ state_translated("sun.sun") }}

result:

below_horizon
Onder de horizon

To achieve this functionality some small changes had to be done in translations loading process: state translations for configured language are loaded to cache at HA start.

Points to consider

• use a different name for a function; suggestions: localized
• state.default.unavailable, state.default.unknown translations are at this moment available only on FE

Possible future improvements

• translating values for attributes
• translating keys

Previous approach to adding this functionality: #65743

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request: Add documentation of state_translated jinja function home-assistant.io#31323

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• I have followed the perfect PR recommendations
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

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

• Documentation added/updated for www.home-assistant.io

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

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• For the updated dependencies - a link to the changelog, or at minimum a diff between library versions is added to the PR description.
• Untested files have been added to .coveragerc.

To help with the load of incoming pull requests:

• I have reviewed two other open pull requests in this repository.

[emontnemery]

Very nice @PiotrMachowski !

Some comments though.

[home-assistant]

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks 👍

Learn more about our pull request process.

[PiotrMachowski]

@emontnemery thank you for your review, I have adjusted the code according to your suggestions

[emontnemery]

Looks great, just a few minor remarks 👍

[emontnemery]

Thanks, @PiotrMachowski 👍

[PiotrMachowski]

Thank you, @emontnemery!

[bdraco]

It looks like we create a thundering heard of executor jobs after this PR.

[bdraco]

#110674

[PiotrMachowski]

It looks like we create a thundering heard of executor jobs after this PR.

@bdraco Sorry ☹️

[bdraco]

No worries at all. It would be great if you could test #110674 to make sure it doesn't cause any regressions in the new functionality

[PiotrMachowski]

Sure, I'll check it out 👍