Use different default base images for Oracle Functions with GraalVM native image

[sachin-pikle]

Hi @alvarosanchez,

For Oracle Functions, we should use the following images as the default base images:

1. Base runtime image=container-registry.oracle.com/os/oraclelinux:8-slim
2. Base build image=container-registry.oracle.com/graalvm/native-image:17-ol8

If users need to override the defaults e.g., if they are building static or mostly static native executables, they can do it using

1. -Dmicronaut.native-image.base-image-run=...
2. -Djib.from.image=...