[YiR] Share slide

[mazevedofs]

Phabricator: https://phabricator.wikimedia.org/T376300

Notes

• This PR adds the ability to share a slide using a system UIActivityViewController
• For that, I'm creating a separate View derived from the slide, creating a snapshot and saving it as a UIImage
• After discussing with Design, we do not have a "preview" step and we're always setting the shared image size to an iPhone-sized image, even when sharing from iPad
• I'm adding the bottom card with the hashtag, even though it was nice to have on the phab ticket

Test Steps

1. Set device to either Italy, Mexico
2. Set primary app language to a supported lang - en, it, es
3. Tap through 5+ articles
4. Go to the developer settings menu, enable the feature flag
5. Background/foreground the app to populate the report
6. Tap profile, you should see the entry point
7. On a slide, click share. Share to a message, slack, etc
8. Verify UI and text
9. Test from iPad
10. Test flow coming from the announcement if possible, to check for coordinator issues