Detect and format timestamp attributes

[spacegaier]

Breaking change

Proposed change

Ensures that timestamps in more-info popus for attributes are properly formatted.

One point to discuss:

• The RegExp I use also matches pure dates without a time element (but not the other way around) => should I add a second RegExp that then checks if it is a pure date and then we call formatDate rather than formatDateTimeWithSeconds as I do currently?
• Adjust the RegExp to not match dates, which solves the point above.
• Added 2nd RegExp for date detection and formatting.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue or discussion:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• 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