Add support for GraalVM

[sgammon]

Adds a JAR publication at jna-graalvm.jar, with accompanying build infrastructure, which provides support for JNA within the context of the Substrate Virtual Machine (SVM).

GraalVM Native Image targets use SVM instead of JVM at runtime. JNA's current strategy of unpacking libraries at runtime works under SVM, but is suboptimal; the binary is native, so it can simply include JNA object code for the current platform directly.

To accomplish this, several GraalVM "feature" implementations are provided in this new publication. By default, regular JNA access is enabled through the JavaNativeAccess feature; this class enables reflection and runtime JNI configurations for downstream projects which use JNA.

Another feature, SubstrateStaticJNA, is experimental because it relies on unstable GraalVM APIs, but instead of loading JNA at runtime from a dynamic library, it builds JNA into the final native image with a static object.

These features are enabled through a resource within META-INF, called native-image.properties, which is picked up by the native image compiler at build time. The new artifact only needs to be present for GraalVM native targets at build time; otherwise, the classes and libraries in jna-graalvm.jar are inert.

Includes tested support for:

• macOS aarch64

• Linux amd64

• feat: add jna-graalvm.jar publication

• feat: add base JavaNativeAccess feature for auto-config of JNA

• feat: add initial implementation of SubstrateStaticJNA feature

• test: sample/test gradle build for native image

• chore: ci config to run native sample