--[BugFix] Get rid of double JSON lookups using HasMember

[jturner65]

Motivation and Context

Using HasMember and then subsequently accessing a JSON value does a double lookup in the JSON document string. Using FindMember will provide an iterator pointing to the desired value or the end of the document if not found.

This PR replaces HasMember lookups with iterator-based FindMember ones. Note : those that remain in URDFParser and SceneDatasetAttributesManager will be removed in the Articulated Object Attributes/Manager PR.

How Has This Been Tested

All Tests in c++ and python pass locally

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have completed my CLA (see CONTRIBUTING)
• I have added tests to cover my changes.
• All new and existing tests passed.