Fix python to js timestamp conversions in logbook traces

[bdraco]

Proposed change

• The websocket version needs the time converted from
  where python stores the decimal

I didn't realize these were accessed outside the logbook model

Is there a better way to fix this? Ideally it would get converted at a sooner place but I'm not sure where that would be best to do that.

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

[balloob]

I don't think that we can do it earlier. On access is the best approach so we don't compute data that won't end up being used.