Replace ANTLR with hand-rolled parser (#917)

Co-authored-by: Kushal Pisavadia <kushi.p@gmail.com>
Co-authored-by: Daniel Chao <daniel.h.chao@gmail.com>

bench/bench.gradle.kts

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 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.
@@ -25,8 +25,6 @@ val graal: Configuration by configurations.creating
 @Suppress("UnstableApiUsage")
 dependencies {
   jmh(projects.pklCore)
-  // necessary because antlr4-runtime is declared as implementation dependency in pkl-core.gradle
-  jmh(libs.antlrRuntime)
   truffle(libs.truffleApi)
   graal(libs.graalCompiler)
 }

bench/gradle.lockfile

@@ -1,7 +1,6 @@
 # This is a Gradle generated file for dependency locking.
 # Manual edits can break the build and are not advised.
 # This file is expected to be part of source control.
-com.tunnelvisionlabs:antlr4-runtime:4.9.0=jmh,jmhCompileClasspath,jmhImplementationDependenciesMetadata,jmhRuntimeClasspath
 net.bytebuddy:byte-buddy:1.15.11=testCompileClasspath,testImplementationDependenciesMetadata,testRuntimeClasspath
 net.sf.jopt-simple:jopt-simple:5.0.4=jmh,jmhCompileClasspath,jmhImplementationDependenciesMetadata,jmhRuntimeClasspath
 org.apache.commons:commons-math3:3.6.1=jmh,jmhCompileClasspath,jmhImplementationDependenciesMetadata,jmhRuntimeClasspath

bench/src/jmh/java/org/pkl/core/parser/ParserBenchmark.java

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 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.