Evaluate if the slug for song is with certain pattern: A/B/C

[lyrifix-admin]

A:

• onion!-abc123
• onion!-xyz123

B:

• onion!-one-ok-rock-abc123
• onion!-one-ok-rock-xyz123

C:

• onion!-one-ok-rock
• Error when adding the same song & artist onion!-one-ok-rock