Move mixin configs to their own sourceset (#5292)

fabric-client-gametest-api-v1/build.gradle

@@ -3,3 +3,26 @@ version = getSubprojectVersion(project)
 loom {
 	accessWidenerPath = file('src/client/resources/fabric-client-gametest-api-v1.classtweaker')
 }
+
+sourceSets {
+	mixinConfig {
+		compileClasspath += configurations.loaderLibraries
+	}
+	client {
+		compileClasspath += mixinConfig.output
+		runtimeClasspath += mixinConfig.output
+	}
+}
+
+configurations {
+	clientImplementation.extendsFrom mixinConfigImplementation
+	clientRuntimeOnly.extendsFrom mixinConfigRuntimeOnly
+}
+
+dependencies {
+	mixinConfigImplementation "net.fabricmc:fabric-loader:${project.loader_version}"
+}
+
+jar {
+	from sourceSets.mixinConfig.output
+}

fabric-renderer-indigo/build.gradle

@@ -9,3 +9,26 @@ moduleDependencies(project, [
 	'fabric-renderer-api-v1',
 	'fabric-rendering-v1'
 ])
+
+sourceSets {
+	mixinConfig {
+		compileClasspath += configurations.loaderLibraries
+	}
+	client {
+		compileClasspath += mixinConfig.output
+		runtimeClasspath += mixinConfig.output
+	}
+}
+
+configurations {
+	clientImplementation.extendsFrom mixinConfigImplementation
+	clientRuntimeOnly.extendsFrom mixinConfigRuntimeOnly
+}
+
+dependencies {
+	mixinConfigImplementation "net.fabricmc:fabric-loader:${project.loader_version}"
+}
+
+jar {
+	from sourceSets.mixinConfig.output
+}