Use strings instead of f-strings for constants

[springstan]

Breaking change

Proposed change

After the discussion in #40436 (comment) I decided to try and remove as many f-strings from constants.
I have changed the following things and split them up via commits:

• Use strings instead of f-strings for HA constants
• Use string instead of f-string for accuweather
• Add and use PRECIPITATION_MILLIMETERS_PER_HOUR constant
• Add and use speed and volume flow rate units
• Use irridation unit in ambient station

There are a lot more constant that use f-strings, but I wanted to correct the most used ones in the code base.

cc @frenck

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)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example entry for configuration.yaml:

# Example configuration.yaml
n/a

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to PR: Add missing unit for signal strength #40436
• Link to documentation pull request:

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
• 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.
• Untested files have been added to .coveragerc.

The integration reached or maintains the following Integration Quality Scale:

• No score or internal
• 🥈 Silver
• 🥇 Gold
• 🏆 Platinum

To help with the load of incoming pull requests:

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

[frenck]

@springstan Could you pick up the merge conflict? I've added this PR to my notification list for cleanup after it.

[springstan]

Sure, solved the merge conflicts ✌️

[frenck]

Thanks, @springstan 👍