[5.1] Subform rows sorting with buttons, addittionaly to drag and drop

[Fedik]

Summary of Changes

Add posibility to sort subform rows with buttons "up" and "down".
Useful for large forms.

Fix for #39092

Testing Instructions

Run npm install
Create a subform somewhere:

<field type="subform" name="subform" label="subform" multiple="true">
  <form>
    <field type="text" name="text" label="Text"/>
  </form>
</field>

And use new up/down button for rows sorting

Actual result BEFORE applying this Pull Request

nothing

Expected result AFTER applying this Pull Request

works

Link to documentations

Please select:

• Documentation link for docs.joomla.org:
• No documentation changes for docs.joomla.org needed
• Pull Request link for manual.joomla.org:
• No documentation changes for manual.joomla.org needed

[Quy]

I have tested this item ✅ successfully on 89a503e

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[AndySDH]

This approach is a bit reductive and I don't feel like it fully addresses #39092. Dragging and dropping is still very bad, and I don't think adding an up and down arrow is enough to call the problem solved...

[viocassel]

I have tested this item ✅ successfully on 89a503e

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[Quy]

RTC

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[LadySolveig]

A heartfelt thanks @Fedik and thanks to the testers @viocassel @Quy