Image selection from media library

[etoledom]

The image placeholder (or editing an image) should let the user pick an existing image from the media library. We're not dealing with uploads in this issue, those will be in #206

[koke]

I had this split into two task in the backlog (picker, upload with progress). Do you think it makes sense to split in two, or are they too interrelated?

[koke]

Moved the selection and upload parts to #206

[koke]

From @etoledom:

This would be the first Image related bridge implementation, so it’s more likely to find unexpected problems. As I see it after experimenting with this topic, the tasks are:

• Send a message from RN to Native with the Add Image button action.
• Receive the message in native app.
• Reuse media picker with to select an image.
• Send the information of the selected image from Native back to RN.
• Handle selected image in RN.

In this case, the media picker is already an independent module and it shouldn’t be too complex to implement it in the GutenbergController. Still, we might encounter unexpected challenges.

Estimation: one week per platform.