[Rubocop] Enforce param type consistency

Overview

As part of our work to upgrade the OpenAPI specs to version 3, consistency in type definition allows for more smoother translation from grape to openApi3 specs.

All type definitions should be string literals belonging to a predefined subset of available types.

Implementation Plan

• Create a new rubocop that triggers when type definition on an endpoint param is not with in the predefined subset of allowed types
• Update documentation to ensure type requirements are clearly defined
• Work through violations of this rule, once complete and either disable the cop where warranted (clusterwide calls), or work with product teams to resolve.