feat(NcActionButton): introduce description prop

[Antreesy]

☑️ Resolves

• There might be a need to use a button as 'action name' + 'description'
• Current solution: name prop + default slot is a bit bulky
• Alternative with this PR: default slot + subline prop

🖼️ Screenshots

Documentation screenshot:

Same content comparison:

🚧 Tasks

• First commit: check if it's non-breaking

🏁 Checklist

• ⛑️ Tests are included or are not applicable
• 📘 Component documentation has been extended, updated or is not applicable
• 2️⃣ Backport to stable8 for maintained Vue 2 version or not applicable

[nimishavijay]

Looks good!

I'm wondering if we should align the icon with the title instead of centering it in the whole action item element. I remember @marcoambrosini had some thoughts about this?

[marcoambrosini]

Yes, to tidy up things visually, the icon should be aligned with the title of the actionbutton

[ShGKme]

I'm wondering if we should align the icon with the title instead of centering it in the whole action item element. I remember @marcoambrosini had some thoughts about this?

It's unrelated, applied to all action items

• [NcActions] Inconsistent icon position #5284

[nimishavijay]

If the icon alignment is a separate issue, approving this PR for default + subline 👍

[ShGKme]

• There might be a need to use a button as 'action name' + 'description'

If this is semantically a description, maybe also name the prop description?

[susnux]

If this is semantically a description, maybe also name the prop description?

I would second that (seems to be also a bit more consistent with our prop names in general).

[Antreesy]

/backport to stable8