access javadoc from jshell

JShell is capable of handling documentation for items in its [SourceCodeAnalysis](https://docs.oracle.com/en/java/javase/11/docs/api/jdk.jshell/jdk/jshell/SourceCodeAnalysis.html) class, and the Python interpreter provides access to Javadocs using the script using the [ghidradoc.py](https://github.com/NationalSecurityAgency/ghidra/blob/75ae8b3c367010ddc9bfcf1efbe9e768ff3bea93/Ghidra/Features/Python/python-src/ghidradoc.py) script. By combining these techniques, it should be possible to make documentation for classes and methods more easily accessible directly from the interpreter.