Handle the fileAction parent property in the multiple files action bar too

[StCyr]

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Is your feature request related to a problem? Please describe.
fileActions cannot be grouped by parent in the multiple files action bar.

That's, when you create lots of fileActions, you can group them under a single parent in the file action menu. But, this doesn't work in the multiple files action bar:

Describe the solution you'd like
Handle the parent property in the multiple files action bar too

https://nextcloud-libraries.github.io/nextcloud-files/classes/FileAction.html#parent

Describe alternatives you've considered
None

Additional context
Here's an example with an app registering lots of fileActions:

Here's the single file menu, you can see it's much better organized: