Improve actions links for current theme on themes.php

[MikeHansenMe]

The links are not escaped in themes.php related #30952

[DrewAPicture]

@MikeHansenMe: Can we get a version of 31365.diff​ minus the unrelated whitespace changes? Also, seems like we should be able to get away with just using admin_url() as we do elsewhere in the admin.

[MikeHansenMe]

@DrewAPicture updated with only the line changes. Also used admin_url like other places in the admin.

[DrewAPicture]

31365.2.diff​ looks good to me. It's worth having core set a good example for itself, though I think the add_query_arg() bits might be a bit much. Moving for commit consideration.

[ocean90]

This code is led with // Pretend you didn't see this.. Rather than adding some admin_url() and add_query_arg() calls I would like to see this section rewritten. Currently it's just a copy of some code for the admin menu.

31365.2.diff​ will break the CSS rules for hiding custom header/background links, see trunk/src/wp-admin/css/admin-menu.css@31573#L616​

Trac ticket: https://core.trac.wordpress.org/ticket/31365

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