To match stable, add creator= and artist= filters to the beatmap
carousel on song select screen. Contrary to stable, this implementation
supports phrase queries with spaces within using double quotes.
The quote handling is not entirely correct (can't nest), but quotes
should rarely happen within names, and it is an edge case of an edge
case - leaving best-effort as is. Test coverage also included.
Introduce unit tests covering parsing for the originally introduced
filtering features. The introduced improvements (lower and upper
interval and decimal point support) also tested.
