Support JDK17

[richardstartin]

Pinot doesn’t run on JDK17 out of the box and various illegal reflective accesses must be removed to improve new user experience. JDK17 support can be improved gradually by removing illegal reflective access in a piecemeal fashion.

[richardstartin]

Remaining blockers to running on JDK17 are:

• illegal reflective access in FunctionInvoker which blindly makes discovered methods accessible. This could be easily replaced with MethodHandles and simply refuse to discover private methods from outside the module.
• Pinot currently cannot run on JDK17 with any combination of --add-opens/--add-exports because of the larray library which uses JDK internals which no longer exist in JDK17.

[gortiz]

Should we close this issue?