Ensure current active dark modes gets used for manually set themes

[spacegaier]

Breaking change

Proposed change

If you manually set a theme for a single Lovelace component/card or view, the active dark mode had no effect, since the function applyThemesOnElement did not automatically consider the active mode.

With this PR we now pull that in always from hass.themes if no input was provided explicitly by the caller. As a result I removed two code snippets from the hassio files, that did the same already explicitly.

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 Light/Dark/Auto modes not applied to themes setup in lovelace views #10291
• 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