Change the input field used for `alt` attributes in the media library views from a text input to a textarea. This gives users more flexibility in resizing the field for easier management of longer alt attributes.
This patch includes a less-common use of `esc_attr` for a `textarea`. This is because the primary usage of the `alt` attribute will be escaped using `esc_attr`, and the value in editing should match the value output on the front end.
Props edent, sabernhardt, afercia, JavierCasares, audrasjb, joedolson.
Fixes#50066.
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