Publish executables for pkldoc, pkl-codegen-java, pkl-codegen-kotlin (#1023)

This adds logic to build and publish the other executables related to Pkl.

These are:

* pkl-doc
* pkl-codegen-kotlin
* pkl-codegen-java

pkl-codegen-kotlin and pkl-codegen-java are published as executable JARs, whereas pkldoc is published both as an executable JAR, and also native executables (matching the set of os/arch supported by Pkl).

The reason this only publishes executable JARs for pkl-codegen-kotlin and pkl-codegen-java is because we expect that the Java requirement is not a problem for these users, and that the native executable provides negligible added value.

As part of this, the following changes are made:

* Introduce `pklJavaExecutable` plugin, which sets up building and publishing of executable JAR.
* Introduce `pklNativeExecutable` plugin, which sets up building and publishing of native executables.
* Introduce `NativeImageBuild` Gradle task, which knows how to build native-image executables.
* Introduce `ExecutableSpec` extension, for projects that publish executables to configure how those executables should be published.
* `./griddles buildNative`, by default, will only build the executable of the host OS/Arch, and will no longer cross-build.
* The target arch of `./gradlew buildNative` can be changed using `-Dpkl.targetArch=<aarch64|amd64>`.
* On linux/amd64 only, with `./gradlew buildNative`, a statically linked executable can be built using `-Dpkl.musl=true`
* Make `javaExecutable` a dependency of `assemble`
* Make `testStartJavaExecutable` a dependency of `check`
* Change name `pklNativeBuild` to `pklNativeLifecycle` to better match the plugin's purpose
* Remove Truffle SVM classes from main source set (don't publish these classes as part of the pkl-cli JAR)
* Change CircleCI definition to publish new executables
* Change CircleCI definition to call `buildNative` instead of individual task names

docs/modules/kotlin-binding/pages/codegen.adoc

@@ -1,6 +1,11 @@
 = Kotlin Code Generator
 include::ROOT:partial$component-attributes.adoc[]
 :uri-pkl-codegen-kotlin-maven-module: {uri-maven-docsite}/artifact/org.pkl-lang/pkl-codegen-kotlin
+:uri-pkl-codegen-kotlin-download: {uri-sonatype-snapshot-download}&a=pkl-cli-codegen-kotlin&e=jar
+
+ifdef::is-release-version[]
+:uri-pkl-codegen-kotlin-download: {github-releases}/pkl-codegen-kotlin
+endif::[]
 
 The Kotlin source code generator reads Pkl classes and generates corresponding Kotlin classes with equally named properties.
 
@@ -83,8 +88,41 @@ To use the library in a Maven project, declare the following dependency:
 [[install-cli]]
 === CLI
 
-The CLI is bundled with the library.
-As we do not currently ship the CLI as a self-contained Jar, we recommend to provision it with a Maven compatible build tool as shown in <<install-library>>.
+The CLI is available as a Java executable.
+
+It works on multiple platforms, and requires a Java 17 (or higher) runtime on the system path.
+
+To download:
+
+[tabs]
+====
+macOS/Linux::
++
+[source,shell]
+[subs="+attributes"]
+----
+curl -L -o pkl-codegen-kotlin '{uri-pkl-codegen-kotlin-download}'
+chmod +x pkl-codegen-kotlin
+./pkl-codegen-kotlin --version
+----
+
+Windows::
++
+[source,PowerShell]
+[subs="+attributes"]
+----
+Invoke-WebRequest '{uri-pkl-codegen-kotlin-download}' -OutFile pkl-codegen-kotlin.bat
+.\pkl-codegen-kotlin --version
+----
+====
+
+This should print something similar to:
+
+[source,shell]
+[subs="+attributes"]
+----
+pkl-codegen-kotlin {pkl-version} (macOS 14.2, Java 17.0.10)
+----
 
 [[usage]]
 == Usage
@@ -103,10 +141,7 @@ For more information, refer to the KDoc documentation.
 
 === CLI
 
-As mentioned in <<install-cli,Installation>>, the CLI is bundled with the library.
-To run the CLI, execute the library Jar or its `org.pkl.codegen.kotlin.Main` main class.
-
-*Synopsis:* `java -cp <classpath> -jar pkl-codegen-kotlin.jar [<options>] <modules>`
+*Synopsis:* `pkl-codegen-kotlin [<options>] <modules>`
 
 `<modules>`::
 The absolute or relative URIs of the modules to generate classes for.
@@ -133,4 +168,4 @@ include::../../pkl-cli/partials/cli-common-options.adoc[]
 == Full Example
 
 For a ready-to-go example with full source code,
-see link:{uri-codegen-kotlin-example}[codegen-kotlin] in the _pkl/pkl-examples_ repository.
+see link:{uri-codegen-kotlin-example}[codegen-kotlin] in the _pkl-jvm-examples_ repository.