[Feature]: Create a mushroom heading card

[BBE-FR]

Requirements

• I have updated Mushroom to the latest available version
• I did a search to see if there is a similar issue or if a pull request is open.

Is your feature request related to a problem?

Improvement and solving limitation of the new heading cards (2024.10).

Describe the solution you'd like

he new heading card introduced in 2024.10 is very versatile, but it lacks some customisations capabilities that typical mushroom cards offer:

• templating option for Icon and icon color.
• templating capability for title / subtitle.
• possibility to customise the embedded entities in the same manner as mushroom badges or mushroom chips (with a templatable version of those entities, similar to chips capabilities)
• eventually a way to select the display of the entities (left/right/centered/justified) like for the chips could be a plus for some usages (optional in my mind, but to be considered)

Describe alternatives you've considered

• Mushroom Title card does not integrate Icon, nor "embedded" entities (but this can be done through subtitle template for exemple).
• Heading cards does not allow to control icon title or subtitle.

exemple 2 sections :

• section on top: new heading card (but without templatable capacity)+mushroom card without content to act as 1x1 buttons
• section below: mushroom title card (without icon or embedded entities)+mushroom card without content to act as 1x1 buttons
• last image: 2 new heading card and a row of chips
  
  

On top of "basic" heading use on top of sections, these card can be used anywhere for a compact horizontal display like below:

Additional context

Some FR can be related to, both:

• on Mushroom side: Heading: Template Entity #1548
• on Frontend side: Extend Heading card functionality 1. Add support for templates, 2. Add support for multi-line Title and Subtitle home-assistant/frontend#22243

If the "template" part has to remain an advanced feature implemented only on mushroom side, lets mushroomise the heading card !