Creates sample app connecting to development server

[fairlydurable]

This is a working sample. I will not snipsync it in this ticket.

I've done some things with this sample that I specifically want to call out.

• Folder System: The samples (just one to start with) are clustered into a thoughtful file structure, in this case under 'java/client'.
• Naming: The samples are clearly named, to coordinate with the Docs website.
• Maven and "standard" Java: The sample is fully configured Maven, including all its complexity, file system, separate interface and implementation files.
• Makefile: - as suggested a while back by Brian, everything can be built and run and cleaned up with simple make commands. I've tuned the logging levels for each target.
• README: Explains the sample, why it is there, offers a little insight, provides paths to the two files of interest, shows how to use the Makefile, mentions the need for multiple terminal sessions.

JIRA: https://temporalio.atlassian.net/browse/EDU-2212