Use `round()` instead of `floor()` when resizing image dimensions.

Updates unit tests.

Props SergeyBiryukov, kitchin.
Fixes #18532.


git-svn-id: https://develop.svn.wordpress.org/trunk@30660 602fd350-edb4-49c9-b593-d223f7449a82
Use `sanitize_mime_type()` instead of `urlencode()` when string-building `<option>` values in `->get_views()` for media list tables.

`urlencode()` was introduced in [28553] via _duck and yours truly.

Got weirder after [29625].

Props birgire.
Fixes #30123.


git-svn-id: https://develop.svn.wordpress.org/trunk@30661 602fd350-edb4-49c9-b593-d223f7449a82