Make media field initialize itself when a new subform row is added

[okonomiyaki3000]

Pull Request for Issue # .

Summary of Changes

Subform repeatable has a function fixScripts which calls a few js initialization functions on a few of the field types that require it. There is a now a better way to handle that kind of thing by having any field that may need initialization listen for an event fired by subform repeatable. In this PR, I am transferring responsibility of one such initialization from subform repeatable to the correct field type itself.

Note: this PR doesn't really fix anything. the media field type already works with repeatable subforms. This just does it in a somewhat better way.

Testing Instructions

Set up a subform containing a media field. There's a subform in the redirect plugin that's simple to use for this purpose.

Open up the form and create new rows. The media field in each new row should function properly.

Expected result

Media field functions normally.

Actual result

Media field functions normally.

Documentation Changes Required

None

[Quy]

I have tested this item ✅ successfully on 83f9b21

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/20230.}

[viocassel]

I have tested this item ✅ successfully on 83f9b21

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/20230.}

[Quy]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/20230.}

[alikon]

@HLeithner please a final response

1 year old rtc pr

[okonomiyaki3000]

OK, I'll get right on it

[HLeithner]

thx

[okonomiyaki3000]

See also #20231