[META] Roadmap to 8.x-1.0 release

Tasks

• #2529178: Convert media type validation code to a constraint
• #2336157: Provide UI for field mapping
• #2578925: Update \Drupal\media_entity\Plugin\views\wizard\Media

Features

• #2577433: Create formatter for displaying Tweets
• #2577441: Create formatter that displays Instagram items
• #2577411: Create simple formatter that displays thumbnails
• #2577449: Create "field_formatter"

Bugs

Tests

• #2339413: Write tests for type plugins implementation

Documentation

• Basic concepts
• Configuration UI
• Type providers
• Metadata handling
• Developer documentation