Introduce a UUID configuration option for API token

[VolkerStolz]

Proposed change

The Entur-service enforces rate-limiting, and the report in #86547 and subsequent discussion indicates that the corresponding header-suffix needs to be unique per instance.

This patch introduces a UUID derived by default as the md5-hash plus salt of the instance URL which should be unique enough. This autogenerated UUID can be overridden in the configuration.

Type of change

• [ ] Dependency upgrade
• [X] 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 #86547
• This PR is related to issue: #66141
• Link to documentation pull request: forthcoming (new default shouldn't require manual configuration anyway)
• Supersedes pull-request: https://github.com/home-assistant/core/pull/87567

Checklist

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

Replacing one pull-request with another ;-)

[home-assistant[bot]]

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

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[VolkerStolz]

Updated. Now I'm really just using a fresh 6-digit number on each startup.

[MartinHjelmare]

It would have been good to update the PR title and description before merging to reflect the code changes.