Add shadow to chips in dark mode

[tobias-groeger]

Currently chips do not have a visible shadow during dark mode.
Make the shadow of the chips dependent on the theme and darken the shadow when dark mode is enabled.

This approach is already used by the Welcome Scenes Card, which applies it specifically for the chips they used.
This is no longer necessary when we apply this modification to all chips.

Additional information

• This PR fixes or closes issue: fixes Chip shadow in dark mode #1343
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• I have followed the contribution guidelines
  • This PR is for a custom-card or documentation change and therefore directed to the main branch.
  • This PR is for a official card or any other directly to the integration related change and therefore directed to the release branch.