Require explicit registration of worker functions, fix CDK circular dependency error

[twelch]

💥This is a breaking change

Implements a new algorithm for assigning geoprocessing and preprocessing functions to nested LambdaStack's. It ensures that worker functions are kept in the same stack as their parent function, in order to avoid circular dependency errors where Lambda invoke permissions are created for lambda resources that are in different LambdaStacks and CDK can't figure out which stack should be created first.

A parent/worker relationship is now explicitly defined by the developer by passing a workers option to GeoprocessingHandler.
If a parent geoprocessing function called boundaryOverlap invokes a worker function called boundaryOverlapWorker then it should be registered as below.

export default new GeoprocessingHandler(kelpPersist, {
  title: "boundaryOverlap",
  description: "boundary overlap",
  executionMode: "async",
  workers: ['boundaryOverlapWorker']
});

• Add workers option to GeoprocessingHandler
• Error if worker used by two different parent functions
• Error if worker is not registered with parent, and suspected it should be. e.g. boundaryOverlapWorker is likely a worker of boundaryOverlap