Add support for Mixin 0.8.4+

[LXGaming]

Note: This PR targets the master branch, For 1.12-stable use #343

This PR adds support for Mixin 0.8.4+ and makes changes to the build.gradle to improve the build.

The following jars are now created:

1. VanillaFix-x.x.x.jar - Includes Mixin 0.8.3 (Mixin 0.8.4+ will not work on 1.12.2)
2. VanillaFix-x.x.x-thin.jar - Excludes Mixin (For resolving Mixin version conflicts)

Important changes:

• Updated Gradle to 7.4.2 and ForgeGradle to v5.1
• Switched mod dependencies to use CurseMaven to fix resolve issue.
• Updated MixinBlockStateContainer* & MixinMagicStitchingSprite* as they used a constructor overwrite which is a custom feature of DimensionalDevelopment/Mixin, this made VanillaFix incompatible in environments using SpongePowered/Mixin *Additional testing may be required to ensure nothing important has been broken by the changes.

Fixes LXGaming/MixinBootstrap#53
Fixes #265
Fixes #296
Fixes #335