[META] Create process sequence from user template

[dbwiddis]

A user template will have some description of the process flow in terms of nodes and edges. This network needs to be translated into executable asynchronous process sequence. The following steps are required:

• Parse the portion of the user template which describes the nodes and edges into a sorted collection of Java objects using Topological Sorting [FEATURE] Parse a JSON Directed Graph into a process sequence #17
• Perform basic validation of the parsed graph, such as matching output and input types [FEATURE] Validate a process flow graph #18
• Provide an API to support process execution which returns a completable future when it is executed, pauses further execution until a collection of predecessor futures complete, and completes its own future after executing [FEATURE] Provide asynchronous process execution API #19
• Integrate this process execution sequence with the actual workflow execution processes. [FEATURE] Create factory class for Workflow Steps #41