Store Tractive data in `config_entry.runtime_data`

[bieniu]

Breaking change

Proposed change

Store Tractive data in config_entry.runtime_data.

EDIT: I added tests for the diagnostics platform so that codecov would not complain.

Type of change

• [ ] Dependency upgrade
• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New integration (thank you!)
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• [ ] Deprecation (breaking change to happen in the future)
• [ ] Breaking change (fix/feature causing existing functionality to break)
• [x] 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:

Checklist

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[home-assistant[bot]]

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

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Code owners of `tractive` can trigger bot actions by commenting: - `@home-assistant close` Closes the pull request. - `@home-assistant rename Awesome new title` Renames the pull request. - `@home-assistant reopen` Reopen the pull request. - `@home-assistant unassign tractive` Removes the current integration label and assignees on the pull request, add the integration domain after the command. - `@home-assistant add-label needs-more-information` Add a label (needs-more-information, problem in dependency, problem in custom component) to the pull request. - `@home-assistant remove-label needs-more-information` Remove a label (needs-more-information, problem in dependency, problem in custom component) on the pull request.

[bieniu]

Codecov complains about lack of tests for the diagnostics platform and pre-commit doesn’t allow to add diagnostics.py to the .codecovrc. Tests for the diagnostics platform are mandatory?