Improve user-facing error messages in HomeWizard Energy

[frenck]

Proposed change

SSIA, small improvement to the error messages that may be user-facing (shown in the UI). Also added translation support to them.

Adjusts the tests to explicitly check for the message to match.

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:

Checklist

• The code change is tested and works locally.
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• Tests have been added to verify that the new code works.

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[home-assistant]

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

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[jpbede]

Looks good, thanks @frenck 👍

Learned something new, didn't know that HomeAssistantError can be translated.