workflowcheck - initial support for Java static analyzer

[cretz]

What was changed

Added initial temporal-workflowcheck project. This is currently considered "beta". See the README for more about the project.

TODO in the near future:

• Turn the TODO at the bottom of temporal-workflowcheck/README.md into a set of issues
• After we have published our first release of this...
  • Update primary README with link to the project in the child dir
  • Update the 3 sample projects herein to reference the project
  • Update samples-java to incorporate workflowcheck