Add config flow to stiebel eltron component

[ThyMYthOS]

Breaking change

Proposed change

This pull request is a first approach to get bronze status for the stiebel_eltron integration.

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

I need some advise how to copy with the fact that a modbus hub is required first in order to setup this integration. Is is possible to perform this setup in the config flow of this integration? Do you have an example how to do it?

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 Ruff (ruff format 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.

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

[home-assistant]

Hi @ThyMYthOS

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!

[home-assistant]

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

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[home-assistant]

Hey there @fucm, mind taking a look at this pull request as it has been labeled with an integration (stiebel_eltron) you are listed as a code owner for? Thanks!

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[joostlek]

I would recommend doing a preliminary PR where we fix all the typing