[GR-47647] Introduce -H:±UnlockExperimentalVMOptions.

[graalvmbot]

This PR implements Explicit Experimental Option Handling. For now, using experimental options is non-fatal but prints a warning. Explicit unlocking will be required in a future release.

Example

$ native-image -H:+ReportExceptionStackTraces -H:+UnlockExperimentalVMOptions -H:+ExitAfterAnalysis -H:-UnlockExperimentalVMOptions -m jdk.httpserver
Warning: The option '-H:+ReportExceptionStackTraces' is experimental and must be enabled via -H:+UnlockExperimentalVMOptions in the future.
Warning: Please re-evaluate whether any experimental option is required, and either remove or unlock it. The build output lists all active experimental options, including where they come from and possible alternatives. If you think an experimental option should be considered as stable, please file an issue.
========================================================================================================================
GraalVM Native Image: Generating 'jdk.httpserver' (executable)...
========================================================================================================================
[1/8] Initializing...                                                                                    (5.0s @ 0.17GB)
 Java version: 21+30, vendor version: Oracle GraalVM 21-dev+30.1
 Graal compiler: optimization level: 2, target machine: x86-64-v3
 C compiler: gcc (linux, x86_64, 12.3.0)
 Garbage collector: Serial GC (max heap size: 80% of RAM)
 1 user-specific feature(s):
 - com.oracle.svm.thirdparty.gson.GsonFeature
------------------------------------------------------------------------------------------------------------------------
 2 Experimental option(s) in use:
 -H:+ReportExceptionStackTraces
   Origin: command line
 -H:+ExitAfterAnalysis
   Origin: command line
------------------------------------------------------------------------------------------------------------------------
...