Custom icon on entity of room card

[aalbouy]

Additional information

• This PR added the possibility to customize the icon of an entity on the card room while maintaining the default behavior

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.