Database: Add *sort fields, bpm, mood, initial_key

Upgrade from schema version 20 to 21. This includes:

- six fields for sort tags
- new fields bpm, mood, initial_key

See https://github.com/strawberrymusicplayer/strawberry/pull/1779#pullrequestreview-3003042802

data/data.qrc

@@ -12,6 +12,7 @@
         <file>schema/schema-18.sql</file>
         <file>schema/schema-19.sql</file>
         <file>schema/schema-20.sql</file>
+        <file>schema/schema-21.sql</file>
         <file>schema/device-schema.sql</file>
         <file>style/strawberry.css</file>
         <file>style/smartplaylistsearchterm.css</file>