Improve configuration and tests for native-image (#509)

* Don't expose JDK internal classes; instead solve msgpack issue with `--initialize-at-run-time`.
* Use quick build mode for non-release builds:  40% faster compilation, 20% smaller executable.
* Remove options that were commented out.
* Also run ServerTest against native executable

pkl-commons-test/src/main/kotlin/org/pkl/commons/test/PklExecutablePaths.kt

@@ -0,0 +1,47 @@
+/**
+ * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pkl.commons.test
+
+import java.nio.file.Files
+import java.nio.file.Path
+import org.pkl.commons.test.FileTestUtils.rootProjectDir
+
+object PklExecutablePaths {
+  val macAarch64: Path = executablePath("pkl-macos-aarch64")
+  val macAmd64: Path = executablePath("pkl-macos-amd64")
+  val linuxAarch64: Path = executablePath("pkl-linux-aarch64")
+  val linuxAmd64: Path = executablePath("pkl-linux-amd64")
+  val alpineAmd64: Path = executablePath("pkl-alpine-linux-amd64")
+  val windowsAmd64: Path = executablePath("pkl-windows-amd64.exe")
+
+  // order (aarch64 before amd64, linux before alpine) affects [firstExisting]
+  val all: List<Path> =
+    listOf(macAarch64, macAmd64, linuxAarch64, linuxAmd64, alpineAmd64, windowsAmd64)
+
+  val existing: List<Path>
+    get() = all.filter(Files::exists)
+
+  val firstExisting: Path
+    get() =
+      existing.firstOrNull()
+        ?: throw AssertionError(
+          "Native executable not found on system. " +
+            "To fix this problem, run `./gradlew assembleNative`."
+        )
+
+  private fun executablePath(name: String): Path =
+    rootProjectDir.resolve("pkl-cli/build/executable").resolve(name)
+}