build: split up into multiple projects, use kotlin DLS

buildSrc/src/main/kotlin/common-java.gradle.kts

@@ -0,0 +1,12 @@
+plugins {
+	id("common");
+}
+
+java {
+	sourceCompatibility = JavaVersion.VERSION_17;
+	targetCompatibility = JavaVersion.VERSION_17;
+
+	toolchain {
+		languageVersion = JavaLanguageVersion.of(17);
+	}
+}

buildSrc/src/main/kotlin/common.gradle.kts

@@ -0,0 +1,22 @@
+plugins {
+	id("java");
+}
+
+version = rootProject.version;
+group = rootProject.group;
+base.archivesName = "${properties["project_name"]}-${project.name}";
+
+tasks.named<JavaCompile>("compileJava") {
+	options.release.set(8);
+}
+
+repositories {
+	mavenCentral();
+}
+
+dependencies {
+	annotationProcessor("com.github.bsideup.jabel:jabel-javac-plugin:0.4.2");
+	compileOnly("com.github.bsideup.jabel:jabel-javac-plugin:0.4.2");
+	testImplementation("org.junit.jupiter:junit-jupiter:5.9.2");
+	testRuntimeOnly("org.junit.platform:junit-platform-launcher");
+}