[MIGRATED] Implement Link destination to another project

[xmatthewx]

Tinker mode for links includes the option to point to a page in another project.

1. In link element editor, user taps 'set destination'
2. In map page picker, user taps 'tinker bolt'
3. Dialog appears, offering to set destination:
   • page in another project
   • web url
4. User taps '...another project'
5. View appears with Discover and Make tab
6. User navigates and tap to open on a project
7. User pans, selects page, taps checkmark
8. Return to element editor

WIP UI in #1549

[xmatthewx]

@vazquez - see comment in inVision. Post final artwork here. Add notes like you see #1671. This is not urgent.

[vazquez]

Context: User taps set destination in the link editor and then tinker ⚡ in the page picker. See #1670 more info.

Tinker Mode

• User taps ⚡
• Dialog appears. User can:
  • link to page in another project ([MIGRATED] Implement Link destination to another project #1672)
  • link to URL
  • tap outside dialog to dismiss
  • tap android back to dismiss

Choose a Project

• User taps A Page in Another Project in dialogue
• Pick a Project view appears
• User selects Project
  • Checkmark does not appear. In other words, confirmation is not needed. The view automatically transitions on tap.

Choose a Page

• User selects a page within the project
  • Bordered selection appears along with icon.
  • When page has been selected, checkmark appears.

Return to Options View

• Upon confirmation, view returns to the Button Options.

[toolness]

This issue has been moved to mozilla/webmaker-core#54.
Please don't comment on it here.