#5099955 state(media): add error handling for updating/deleting media items

Changes proposed in this Pull Request

It seems like we didn’t have any error handling in place for editing and deleting media items.

• Add basic error handling for editing and deleting media items
• Remove flux actions from those data layer handlers as they weren’t doing anything anymore

Testing instructions

Depending on your browser to simulate failures when processing media files like mentioned above enable request blocking for the following URLs:

• deleting: https://public-api.wordpress.com/rest/v1.1/sites/[YOUR-SITE-ID]/media/*/delete
• editing: https://public-api.wordpress.com/rest/v1.1/sites/[YOUR-SITE-ID]/media/*/edit

Then open the media library and try to edit a media item (e.g. rotate, flip or crop an item) and delete a media item. In both cases you should see an error notice appearing in the top right which says it couldn’t handle the corresponding action.