#64832 Fix Upload Plugin form layout use flex box for file and submit

[PANawkar]

Fix the Upload Plugin/theme upload layout alignment

Wrap file input and Install Now in wp-upload-form-box; style as flex row so the button stays in the same grey box (fixes fr_FR and
avoids absolute positioning with top: auto, dropping the submit below). Update themes.css and themes-rtl.css; stack on narrow viewports.

Trac ticket: https://core.trac.wordpress.org/ticket/64832

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[joedolson]

This change just restores the problem previously fixed in https://core.trac.wordpress.org/ticket/64065. Let's try to find a solution that allows us to keep the larger drop area.

[PANawkar]

@joedolson, please let me know if any changes are needed in this PR.

[joedolson]

@PANawkar Unfortunately, it doesn't seem to me that these changes have solved anything. The drop area is still only the small file input. The goal of the prior change was to make the file input cover the entire form space, so that the drop area is easier to hit; but this doesn't do that.

I'll look at it and see if there are other options.

[github-actions]

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 62090
GitHub commit: 77850fb

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.