Add Camunda dependencies to mod_camunda

To summarize the work done on this

• Create mod-camunda that extends spring-module-core
• Bring in Camunda dependencies to embed the workflow engine
• Create a pattern for the project structure (where to store files, assets, etc.)
• Develop and test multi-tenancy
• Create a few sample processes that demonstrate how to use common activities within Camunda and confirm that will work in multi-tenant environment
• Determine which Camunda APIs to expose for mod-workflow

Detailed documentation can be found in the mod-camunda github README.
https://github.com/folio-org/mod-camunda