Add reflection hints for io.netty.util.internal.PlatformDependent0 when JDK 21

[violetagg]

What does this PR do?

Netty project has added a reflection specific for JDK 21 with netty/netty#13366
The reflection hints need to be updated to cover also this JDK version.

The exception below is observed in the logs when running without these hints:

java.lang.NoSuchMethodException: java.nio.DirectByteBuffer.<init>(long, long)
        at [email protected]/java.lang.Class.checkMethod(DynamicHub.java:1065) ~[spring.graalvm:na]
        at [email protected]/java.lang.Class.getConstructor0(DynamicHub.java:1228) ~[spring.graalvm:na]
        at [email protected]/java.lang.Class.getDeclaredConstructor(DynamicHub.java:2930) ~[spring.graalvm:na]
        at io.netty.util.internal.PlatformDependent0$5.run(PlatformDependent0.java:291) ~[na:na]
        at [email protected]/java.security.AccessController.executePrivileged(AccessController.java:129) ~[na:na]
        at [email protected]/java.security.AccessController.doPrivileged(AccessController.java:319) ~[na:na]
        at io.netty.util.internal.PlatformDependent0.<clinit>(PlatformDependent0.java:286) ~[na:na]
        at io.netty.util.internal.PlatformDependent.isAndroid(PlatformDependent.java:331) ~[na:na]
        at io.netty.util.internal.PlatformDependent.<clinit>(PlatformDependent.java:86) ~[na:na]

Code sections where the PR accesses files, network, docker or some external service

• N/A

Checklist before merging

• I have considered including reachability metadata directly in the library or the framework (see our contributing document)
• I am the original author of all content provided in the pull request, and I did not copy the content from any other source (see the tests section from our contributing document)
• N/A [ ] For all tests where I am not the sole author, I have added a comment that proves I may publish them under the specified license (see the tests section from our contributing document)
• I have properly formatted metadata files (see our formatting guide)
• N/A [ ] I have added thorough tests (see the tests section from our contributing document)
• N/A [ ] I have filled all places where my pull request accesses files, network, docker, or any other external service (see the section above)

Test is not provided because the current Gradle version that the project uses does not support JDK21.

[violetagg]

cc @bclozel @sdeleuze

[sdeleuze]

Looks good to me.
@dnestoro Please merge it.

[violetagg]

@sdeleuze @dnestoro Thanks!