Fix several issues with the Fabric API jar

- Bundle the core API inside the Fabric API jar for now, to ensure
   that ResourceLocation is remapped.

 - Add a dummy fabric.mod.json file to the API. We'll remove this once
   https://github.com/FabricMC/fabric-loom/pull/749 is released.

projects/fabric-api/build.gradle.kts

@@ -1,3 +1,5 @@
+import cc.tweaked.gradle.mavenDependencies
+
 plugins {
     id("cc-tweaked.fabric")
     id("cc-tweaked.publishing")
@@ -15,3 +17,30 @@ dependencies {
     api(project(":core-api"))
     compileOnly(project(":forge-stubs"))
 }
+
+tasks.jar {
+    manifest {
+        attributes["Fabric-Loom-Remap"] = "true"
+    }
+
+    from(project(":core-api").sourceSets.main.get().output) // TODO(1.19.3): Remove when we've fixed GenericSource
+    from("src/main/modJson") // TODO: Remove once Loom 1.1 is out.
+}
+
+// TODO(1.19.3): Remove when GenericSource no longer uses ResourceLocation. This forces us to bundle the core API with
+//  the Fabric API, in order to remap those classes.
+
+tasks.sourcesJar {
+    from(project(":core-api").sourceSets.main.get().allJava)
+}
+
+tasks.withType(GenerateModuleMetadata::class).configureEach { isEnabled = false }
+publishing {
+    publications {
+        named("maven", MavenPublication::class) {
+            mavenDependencies {
+                exclude(dependencies.create("cc.tweaked:"))
+            }
+        }
+    }
+}

projects/fabric-api/src/main/modJson/fabric.mod.json

@@ -0,0 +1,9 @@
+{
+    "schemaVersion": 1,
+    "id": "computercraft_api_stub",
+    "version": "1.0",
+    "name": "ComputerCraft API",
+    "description": "A placeholder mod to ensure Loom deobfuscates the API jar.",
+    "license": "ComputerCraft Public License (https://raw.githubusercontent.com/dan200/ComputerCraft/master/LICENSE)",
+    "environment": "*"
+}