invokedynamic : remove/replace getModuleGroup

[SylvainJuge]

The ExperimentalInstrumentationModule.getModuleGroup() method was introduced to deal with instrumentation that requires access to shared classes: some instrumentation modules rely on a common library used by multiple instrumentation modules.

The current getModuleGroup method allows to use a string key that will make the instrumentation modules using the same key to be loaded in the same classloader, hence providing the access to the shared classes.

Ideally, when using indy:

• we should load every instrumentation module in its own isolated classoader
• we should provide the same class visibility semantics as the compile-time classpath of the instrumentation module, without having to explicitly ask for it (the current solution requires multiple modules to share the same key and finding dependencies is trial and error).

[SylvainJuge]

In #18707 , I am trying to implement this using:

• a common module classloader (one per instrumented classloader) where common classes are injected and loaded
• heuristic on class package: instrumentation classes in *.common.* package loaded in this shared classloader
• instrumentation module CL delegates to the common classloader

[SylvainJuge]

Alternative and simpler approach implemented in #18859