Move to jar / *Jar tasks instead of compileJava

Prior to this PR, classes were compiled multiple times (presumably for each sourceset, so at-least twice in normal projects)

Common/build.gradle

@@ -35,6 +35,7 @@ processResources {
         expand buildProps
     }
 }
+
 publishing {
     publications {
         mavenJava(MavenPublication) {

Fabric/build.gradle

@@ -16,6 +16,12 @@ dependencies {
 }
 
 loom {
+    mods {
+        register(mod_id) {
+            sourceSet sourceSets.main
+            sourceSet project(":Common").sourceSets.main
+        }
+    }
     runs {
         client {
             client()
@@ -32,9 +38,7 @@ loom {
     }
 }
 
-
 processResources {
-    from project(":Common").sourceSets.main.resources
     inputs.property "version", project.version
 
     filesMatching("fabric.mod.json") {
@@ -42,14 +46,16 @@ processResources {
     }
 }
 
-tasks.withType(JavaCompile) {
-    source(project(":Common").sourceSets.main.allSource)
+jar {
+    from project(":Common").sourceSets.main.output
 }
 
-jar {
-    from("LICENSE") {
-        rename { "${it}_${mod_name}" }
-    }
+javadoc {
+    source project(":Common").sourceSets.main.allJava
+}
+
+sourcesJar {
+    from project(":Common").sourceSets.main.allSource
 }
 
 publishing {

Forge/build.gradle

@@ -77,14 +77,17 @@ dependencies {
     compileOnly project(":Common")
 }
 
-tasks.withType(JavaCompile) {
-    source(project(":Common").sourceSets.main.allSource)
+jar {
+    from project(":Common").sourceSets.main.output
 }
 
-processResources {
-    from project(":Common").sourceSets.main.resources
+javadoc {
+    source project(":Common").sourceSets.main.allJava
 }
 
+sourcesJar {
+    from project(":Common").sourceSets.main.allSource
+}
 
 jar.finalizedBy('reobfJar')