clean up GT++ code

[boubou19]

according to our own policy, GTPlusPlus support is GTNH only, so with Dream's approval, i yeeted the following
compats:

• Big Reactors
• IC2 classic
• Pneumaticraft
• More Planets
• Psychedelicraft
• Beyond Reality Core
• Simply Jetpacks
• RFTools
• CompactWindmills
• GrowthCraft
• ThermalFoundation
• IHL
• Mekanism
• Redtech
• xReliquary

Other things i also did:

• I removed the use of LoadedMods.java, as we now have a fancy GT5U enum for mod ids
• i optimized imports
• removed hazmat utility class
• i started to put all the recipes in the same place (only some pyrolyse oven for now)

Config changes:

• removed # Makes LuV+ Casings and Hulls more difficult to craft. [default: false] B:enableHarderRecipesForHighTierCasings=false and its usages because it's both by default off within GTPP and in the modpack config

[github-actions]

Warning: 2 uncommitted changes
#590

[miozune]

Can you also remove HazmatUtils if it's within the scope of this PR? It was moved to GT and does nothing

[boubou19]

sure