URenderPipeline: Fix blend state with default/mc shaders on 1.17-1.20.6, properly

The previous workaround for this (5f02456) had incorrectly assumed
that all our code running after it would only touch the global GL state
but not MC's GlBlendState global state, however `BlendState.activate`
(and `UGraphics.Global.blendState`, which forwards to that) does
actually set MC's GlBlendState global state as well, rendering the
workaround largely ineffective.

This commit fixes that by adding an internal method to `BlendState`
which bypasses MC's `GlBlendState`, and then using that method from the
workaround in `URenderPipeline` as well as `ManagedGlState`.

Linear: EM-3509
GitHub: #120

Author: Johni0702

src/main/kotlin/gg/essential/universal/render/ManagedGlState.kt

@@ -126,8 +126,7 @@ internal class ManagedGlState(
         }
         if (curr.blendState != blendState) {
             curr.blendState = blendState
-            @Suppress("DEPRECATION")
-            blendState.activate()
+            blendState.activateWithoutChangingMcBlendState()
         }
         if (curr.colorMask != colorMask) {
             curr.colorMask = colorMask

src/main/kotlin/gg/essential/universal/render/URenderPipeline.kt

@@ -132,7 +132,7 @@ class URenderPipeline private constructor(
         //$$     val prevBlendState = BlendState.active()
         //$$     shaderProgram.bind()
         //$$     shaderProgram.unbind()
-        //$$     UGraphics.Globals.blendState(prevBlendState)
+        //$$     prevBlendState.activateWithoutChangingMcBlendState()
         //$$ }
         //#endif
     }

src/main/kotlin/gg/essential/universal/shader/BlendState.kt

@@ -60,6 +60,8 @@ data class BlendState(
     fun activate() = applyState()
     //#endif
 
+    internal fun activateWithoutChangingMcBlendState() = applyState()
+
     @Suppress("DEPRECATION")
     private fun applyState() {
         if (enabled) {