Media: Add support for tapping to remove media from post

[rachelmcr]

It would be helpful to have the option to tap to delete media from the post (e.g. an 'x' to tap to remove the media), instead of having to backspace over the media. Alternately, the option to tap the image and backspace (instead of placing the cursor after the image and then backspacing) would be helpful.

For comparison, the visual web editor has a popup that appears when you click on an image in the editor, with an 'x' to remove the image:

Related Android editor issue: wordpress-mobile/WordPress-Editor-Android#301

[rachelmcr]

Another reason for adding this support: consistency for removing media from the post.

Currently, you cannot backspace over a failed media upload to remove it. Instead, you have to tap on the image and choose to remove the failed upload. Adding support for tapping to remove successfully uploaded media would create a consistent tap-to-remove experience.