Add ability to search media library when adding media

[rachelmcr]

In the Media section of the app, you can search within your media library for a specific image.

However, when adding media from the media library to a post (in the post body or as a featured image) there is no option to search the media library for a specific image.

It would be helpful to add search to the media picker when adding media from the media library in the editor.

(Requested by a user in an app review.)

[rachelmcr]

This came up again in support (126787-h):

When I publish a post with this app and I need to upload a photo of the library I can not find old photos. It would be very useful and functional that could filter the photos in the library by name.

[rachelmcr]

This came up again in support (145812-h) and a recent app review.

[rachelmcr]

This came up again in an app review:

It's a good app but I noticed you can't search for old pictures within the app database. You have to keep scrolling down endlessly.

[rachelmcr]

Another request in an app review:

Please add a search function for Mediagallery. When i write a Post and add a Picture i must long scrolling to find it.

[maxme]

I'm pretty sure the search feature would be even better using our future Document Provider - related to wordpress-mobile/WordPress-Android#3789