Update to Gradle 8.x

- Update to Loom 1.2 and FG 6.0. ForgeGradle has changed how it
   generates the runXyz tasks, which makes running our tests much
   harder. I've raised an issue upstream, but for now we do some nasty
   poking of internals.

 - Fix Sodium/Iris tests. Loom 1.1 changed how remapped configurations
   are generated - we create a dummy source set and associate the
   remapped configuration with that. All nasty stuff.

 - Publish the common library. I'm not a fan of this, but given how much
   internals I'm poking elsewhere, should probably get off my high
   horse.

 - Add renderdoc support to the client gametests, enabled with
   -Prenderdoc.

buildSrc/src/main/kotlin/cc/tweaked/gradle/MinecraftExec.kt

@@ -32,11 +32,14 @@ abstract class ClientJavaExec : JavaExec() {
         usesService(clientRunner)
     }
 
+    @get:Input
+    val renderdoc get() = project.hasProperty("renderdoc")
+
     /**
      * When [false], tests will not be run automatically, allowing the user to debug rendering.
      */
     @get:Input
-    val clientDebug get() = project.hasProperty("clientDebug")
+    val clientDebug get() = renderdoc || project.hasProperty("clientDebug")
 
     /**
      * When [false], tests will not run under a framebuffer.
@@ -63,6 +66,7 @@ abstract class ClientJavaExec : JavaExec() {
         task.copyToFull(this)
 
         if (!clientDebug) systemProperty("cctest.client", "")
+        if (renderdoc) environment("LD_PRELOAD", "/usr/lib/librenderdoc.so")
         systemProperty("cctest.gametest-report", testResults.get().asFile.absoluteFile)
         workingDir(project.buildDir.resolve("gametest").resolve(name))
     }