Add a couple of tests for pocket computers

- Ensure they're correctly synced to the client. This definitely isn't
   comprehensive, but doing anything further probably involves multiple
   players, which is tricky.

 - Quick rendering test for in-hand computers.

buildSrc/src/main/kotlin/cc/tweaked/gradle/MinecraftExec.kt

@@ -40,12 +40,6 @@ abstract class ClientJavaExec : JavaExec() {
     @get:Input
     val useFramebuffer get() = !clientDebug && !project.hasProperty("clientNoFramebuffer")
 
-    /**
-     * The folder screenshots are written to.
-     */
-    @get:OutputDirectory
-    val screenshots = project.layout.buildDirectory.dir("testScreenshots")
-
     /**
      * The path test results are written to.
      */
@@ -109,11 +103,6 @@ abstract class ClientJavaExec : JavaExec() {
         } else {
             super.exec()
         }
-
-        fsOperations.copy {
-            from(workingDir.resolve("screenshots"))
-            into(screenshots)
-        }
     }
 
     @get:Inject