Add support for other image based widgets [#3476380]

Problem/Motivation

The module doesn't currently support other widgets such as the SVG image module which doesn't extend ImageWidget.

Proposed resolution

The module should check if the module's field_types plugin definition supports the image field type and it extends FileWidget (ImageWidget already does).

Issue fork ai_image_alt_text-3476380

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3476380-improve-widget-support changes, plain diff MR !3
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