CIDEVSTC-49 - Refactors Parameter-based DM service methods to respect IonObjects


- Refactors preload for ParameterFunction resources to use a service method instead of independent behavior.
- Adds new service method `create_parameter` which accepts a ParameterContext resource and mimics most of the behavior used in preload.
- Adds new class method `get_coverage_parameter`, creates a coverage-model based ParameterContext object using the ParameterContext IonObject
- Adds new class method `get_coverage_function`, creates a coverage-model based ParameterFunction object using the ParameterFunction IonObject
- Adds new service method `load_parameter_function` which behaves like the preload for parameter functions, this allows service clients to have the same functionality as loading a preloaded resource.
  - Parses information from a row like dictionary
  - Creates an appropriate data process definition
- Changes DM tests to use the new service methods
- Updates types.py to be more robust and not geared only towards preload but for general cases as well.