Editor: Handles media from share action

[antonis]

Fixes #15735

Adds handling for media from share action.

Notes:

• Reverting f241d1e fixes the image sharing issue but reintroduces Sharing text from other apps results in infinite loading gutenberg-mobile#4040. I haven't found a cleaner way to resolve both issues at this point.
• Known issue: when sharing multiple images the images are added twice

To test:

Share image/video

1. Open Files and select an image by tapping it.
2. Tap the Share icon in the bottom menu bar.
3. Select WordPress, then choose a site to share to.
4. Select "Add to new post".
5. Verify that the image is successfully added to the post

Image sharing

image.mp4

Video sharing

video.mp4

Share text action

1. Select some text (e.g. on the browser)
2. Choose the share action on the context menu and select share
3. Select the WordPress app from this PR
4. Select a site
5. Verify that the editor opens with the correct shared content

Text sharing

text.mp4

Regression Notes

1. Potential unintended areas of impact
   Share functionality

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   Relied on existing tests and manually tested the share text action

3. What automated tests I added (or what prevented me from doing so)
   The code changes on the EditPostActivity are not easily testable

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[peril-wordpress-mobile]

You can trigger optional UI/connected tests for these changes by visiting CircleCI here.

[peril-wordpress-mobile]

You can test the changes on this Pull Request by downloading the APKs:

• Jetpack-pr-15864-build-118530.apk

• WordPress-pr-15864-build-118530.apk

[ashiagr]

Thank you for the fix, @antonis! It works as described. 🙌

Regarding the known issue:

sometime when sharing multiple images the images are added twice

Are we tracking it as an issue? If not, I'd suggest creating one before we merge the PR.

[antonis]

Thank you for your review @ashiagr 🙇‍♂️

Are we tracking it as an issue? If not, I'd suggest creating one before we merge the PR.

I opened an issue and updated the PR description.