Make "button row" name optional to be consistent with "button card" and "buttons row"

[spacegaier]

Breaking change

Not breaking, since officially no one should have been setting an entity yet for this row. If they were and did not specify an override icon until now, then the "hass:remote" icon that they had so far will be replaced by the entity icon.

Proposed change

Making the behavior of button row and button card consistent: name is now optional and we use the entity friendly name if we have one. We also use the icon from it, if no override icon is provided.

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: Entities card: Button row name now optional home-assistant.io#16261

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

[bramkragten]

OK to merge after documentation PR made