Allow the_post_format_image() to choose an image size late in the game.

props davidwilliamson, SergeyBiryukov. fixes #23945.

git-svn-id: https://core.svn.wordpress.org/trunk@24079 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add a post_format_meta filter.

props alexkingorg. fixes #24162.

git-svn-id: https://core.svn.wordpress.org/trunk@24080 1a063a9b-81f0-0310-95a4-ce76da25c4cd