test: add Intervals Palette Tests (Beginner + Advanced)

Adds 'Intervals Palette Tests Beginner' (18 blocks) testing settransposition
with perfect fifth interval (7 semitones).

Adds 'Intervals Palette Tests Advanced' (18 blocks) testing semitoneinterval
with tritone (6 semitones).

Follows naming convention from PR sugarlabs#5747. Rebased on current master (938a676).
Total blocks: 694 -> 732 (38 new blocks + 2 nameddo calls).

Author: Ashutoshx7