Make end armor trimmable / add end trim materials

[OpenBagTwo]

Coulda sworn there was an issue asking for this, but anyway, my 9yo has been begging for it 😆

A few notes:

• Crystalite is too busy for trims to appear or really make sense
• Armored Elytra is trimmable, and I had to change the item texture to make the trim overlay not look like garbage (the alternative would be to create a custom trim overlay, a la this example)
• No datagen (I just did it within an interactive Python session), because:
  • I'm still not 💯 on how to run datagen for BE
  • I'm not sure how to get at the Thallasium and Terminite armor pieces within the mod, given the current structure
  • I think work would need to be put in upstream (into WorldWeaver) to handle generating the myriad {material}_{piece}_{trim}_trim.json files

[OpenBagTwo]

I also added amber gems and crystal shards as trim materials.

Again: did the datagen in Python, which is why they're not in the "generated" folder—if you implement a Wover model data provider, you'll obviously want to move everything there.

[OpenBagTwo]

With 433b82b, this PR now additionally updates the language file entries for the music discs. Alternatively, @frankbauer, you could update the datagen to simply specify the old locations for the jukebox song names. That is, there's nothing to say that in the translate key in jukebox_song/endseeker.json:

BetterEnd/src/main/generated/data/betterend/jukebox_song/endseeker.json

Line 4 in 2b95458

"translate": "jukebox_song.betterend.endseeker"

couldn't still point to: item.betterend.music_disc_endseeker.desc