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

Signed-off-by: Sam Gammon <[email protected]>

Signed-off-by: Sam Gammon <[email protected]>

Signed-off-by: Sam Gammon <[email protected]>

Signed-off-by: Sam Gammon <[email protected]>

Signed-off-by: Sam Gammon <[email protected]>

Signed-off-by: Sam Gammon <[email protected]>

Signed-off-by: Sam Gammon <[email protected]>

Signed-off-by: Sam Gammon <[email protected]>

Signed-off-by: Sam Gammon <[email protected]>

Signed-off-by: Sam Gammon <[email protected]>

Signed-off-by: Sam Gammon <[email protected]>

When linked statically on GraalVM, JNI symbols declared in the
overloaded form cannot be resolved. Luckily, all of `Native`'s
callsites are in `Pointer` or itself, and all `native` methods
of `Native` are non-public.

This PR adjusts the JNA C API to avoid using overloaded `read`,
`write`, or `getDirectByteBuffer`. Callsites are amended in
`Pointer` accordingly.

Signed-off-by: Sam Gammon <[email protected]>

Signed-off-by: Sam Gammon <[email protected]>

Signed-off-by: Sam Gammon <[email protected]>