Gradle 8 tests, perf/memory optimisations (#796)

* Add gradle 8 tests
Reuse gradle home between tests
Misc perf and mem optimisations

* Fix build warning.

* Added multi mc version test

* Use server launcher in ServerRunner

Co-authored-by: Luna <62033805+Luna5ama@users.noreply.github.com>

build.gradle

@@ -111,7 +111,6 @@ dependencies {
 	testImplementation ('io.javalin:javalin:5.1.2') {
 		exclude group: 'org.jetbrains.kotlin'
 	}
-	testImplementation 'net.fabricmc:fabric-installer:0.9.0'
 	testImplementation 'org.mockito:mockito-core:4.8.0'
 
 	compileOnly 'org.jetbrains:annotations:23.0.0'
@@ -194,6 +193,7 @@ jacocoTestReport {
 
 test {
 	maxHeapSize = "2560m"
+	jvmArgs "-XX:+HeapDumpOnOutOfMemoryError"
 	useJUnitPlatform()
 
 	// Forward system prop onto tests.