Enhancement request: Support field return specifications

[ryanstryker]

Summary

Allow users to specify the fields to be returned by endpoints as documented here: https://help.tableau.com/current/api/rest_api/en-us/REST/rest_api_concepts_fields.htm

Request Type

Type 1: This behavior is already supported by API endpoints (though buggy in the case of all for some endpoints).

Description

Currently, only the default fields are returned. If more data is needed to populate attributes for a particular item, additional calls have to be made for individual users, workbooks, etc. This results in many unnecessary calls to the same endpoints.

An ancillary issue to this request is that there are (and may continue to be) attributes the API is a able return that the TSC models aren't aware of. There should be a generic way to retrieve values for named fields in the response.