Convert "Search" to use SQLite Full-Text-Search instead of pattern matching

[haroldadmin]

The current search implementation uses the LIKE operator to compare launches, launchpads, and rockets against the given query. This is okay, but a better implementation would use Room's FTS support for this.

Required tasks:

• Create FTS tables to index launches, rockets and launchpads
• Add a DB creation callback to rebuild FTS indices in onCreate() method of the RoomDatabase.Callback class
• Refactor Search's ViewModel to use these FTS tables for searching

Bonus tasks:

• Use a custom ranking function to order results by their relevance with the help of matchinfo