Implement Pkl binary renderer and parser (#1203)

Implements a binary renderer for Pkl values, which is a lossless capturing of Pkl data.

This follows the pkl binary format that is already used with `pkl server` calls, and is
made available as a Java API and also an in-language API.

Also, introduces a binary parser into the corresponding `PObject` types in Java.

pkl-server/pkl-server.gradle.kts

@@ -28,17 +28,7 @@ dependencies {
   testImplementation(projects.pklCommonsTest)
 }
 
-tasks.test {
-  inputs
-    .dir("src/test/files/SnippetTests/input")
-    .withPropertyName("snippetTestsInput")
-    .withPathSensitivity(PathSensitivity.RELATIVE)
-  inputs
-    .dir("src/test/files/SnippetTests/output")
-    .withPropertyName("snippetTestsOutput")
-    .withPathSensitivity(PathSensitivity.RELATIVE)
-  exclude("**/NativeServerTest.*")
-}
+tasks.test { exclude("**/NativeServerTest.*") }
 
 private fun Test.configureNativeTest() {
   testClassesDirs = files(tasks.test.get().testClassesDirs)