[GR-49525] Flag '--future-defaults=<option>' for gentle migration to the correct Native Image semantics.

[graalvmbot]

Introduced --future-defaults=[all|run-time-initialized-jdk|none] that allows for gentle migration to the future default behaviors of Native Image. The first enabled behavior is run-time-initialized-jdk that moves away from build-time initialization of the JDK.

Note: what makes it into the future-defaults must not be an experimental feature that can be rolled back. The changes must be aligning native image with the Java spec and must be thoroughly reviewed.

Value none resets all previous settings and can be set only on the command line. Other options can be placed in JAR files as well.

Build Output

 Recommendations:
 G1GC: Use the G1 GC ('--gc=G1') for improved latency and throughput.
 PGO:  Use Profile-Guided Optimizations ('--pgo') for improved throughput.
 FUTR: Use --future-defaults=all to use the correct semantics and prepare for future releases.
 HEAP: Set max heap for improved and more predictable memory usage.
 CPU:  Enable more CPU features with '-march=native' for improved performance.

[jerboaa]

@vjovanov Could you please add a description to this PR? It shows up empty over here :-/