[5.1] Use Dialog field for Modal_Category

[Fedik]

Summary of Changes

Changing Modal_Category field to use new modal dialog.
The same as #40462 but for Category.

Testing Instructions

Create a menu for category,
Select/edit value in "Choose a Category" field

Actual result BEFORE applying this Pull Request

Works

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: Content select in modal Manual#178
• No documentation changes for manual.joomla.org needed

Reference:

• [5.0] Generic ModalSelect field #40462

[Quy]

I have tested this item ✅ successfully on 88cb998

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[viocassel]

I have tested this item ✅ successfully on 88cb998

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[Quy]

RTC

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[LadySolveig]

Thank you @Fedik !
And thanks to the diligent testers @viocassel @Quy