Workflow creation and assignment definition

As of HG1705 CMSWEB cycle, we've tighten the request spec validation for both creation and assignment. In summary they are:

• there is a specific set of parameters that must be provided during request creation (optional=False). There are also optional parameters that have a default value in ReqMgr;
• there is a specific set of parameters that must be provided during request assignment (assign_optional=False). There are also optional parameters that have a default value in ReqMgr;
• unknown arguments (not defined in the spec files) are no longer accepted/removed and the request will fail validation. Moreover, arguments are case-sensitive;
• there are a few arguments that are allowed both at creation and at assignment. Besides those, you must provide only creation or only assignment parameters, according to the operation you want to accomplish.
• inner Task/Step dictionary (for TaskChain/StepChain) are also validated.

Request type dependencies

The definition of these arguments follow a hierarchy where StdBase contains the base definition for all workflows. See 'getWorkloadCreateArgs', 'getWorkloadAssignArgs' and 'getChainCreateArgs'. Most of the other requests inherit from StdBase and they can override the base arguments definition with specific arguments or data type, see each of them according to the request type you want to create. In addition to that, data processing requests (requests that always have an input dataset) inherit the arguments definition from DataProcessing, which also has StdBase as a super class. This flowchart should make these dependencies clear:

So, for instance, if one wants to create a MonteCarloFromGEN request, you need to:

1. get the StdBase create args
2. update them with the DataProcessing create args
3. and finally update those with the MonteCarloFromGEN create args. this gives you the final list of arguments allowed, their default values, their expected data type, their validate function and so so.