Add modal for creating sharing

[ildyria]

This replaces the sharing form directly in the page.
Yes, it adds a click but it makes it easier for the user to understand the process.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.69%. Comparing base (6fe7bf5) to head (8b25712).
Report is 15 commits behind head on master.

Additional details and impacted files

[ildyria]

@LycheeOrg/reviewers ready for reviews. :)