Eslium Backport

Initial 1.21.11 port of Eslium.

Fixes:

• Fixed a startup crash where the config directory was null during client init (config is now resolved lazily through FabricLoader)
• Fixed the potion mixin targeting a method that no longer exists in 1.21.11
• Fixed a crash when opening the config screen caused by a duplicate background blur within a single frame

Included:

• Full feature port from the 1.16.5 build
• Anchors, placement, throwables, tools, weapons, combat and consumables
• Elytras, firework, windcharge, interactables, redstone and cooldowns
• Pose, optout, swap, crystals and minecarts predictions
• Config parity with 19 sections plus simulatedDesync
• In-game configuration through Mod Menu (optional)
• README configuration documentation