The black mages over all of DMU's bad music

[new version: normalised tracks to -12LUFS in line with other XIV tracks)

Inspired by https://xivmodarchive.com/modid/163464

This is an extension of the above to replace both phase 3, 4, and 5 of DMU with music by the black mages.

Showcase: https://www.youtube.com/watch?v=KaIBejLsSmo

We've got:

- Cutscene/p3 start: https://www.youtube.com/watch?v=Bs67QjagDtM (ff6 battle theme)
- Bowels of agony: https://www.youtube.com/watch?v=NQD089JfDCk (ff1 battle scene)
- Black hole: https://www.youtube.com/watch?v=Iz9RXsMKExo (Neo Exdeath)
- Kefka says: https://www.youtube.com/watch?v=lRhPgzHb_KA (ff6 decisive battle)
- P5: https://www.youtube.com/watch?v=QSEI7tkA0_k (dancing mad)

I used the internet archive's flac versions of these tracks transcoded as best I could get the, so they should be decent quality. Syncs up quite nicely too!

P1 and P2 are unchanged.