Draft: Proof-of-Concept for Supporting Multiple Sources of Location and Object Metadata

[kumar-sanjeeev]

This is a draft PR to showcase proof-of-concept of accepting multiple sources of locations an objects metadata.

• add an add_metadata method to the World, Location, and Object classes, replacing the set_metadata method.
• update the EntityMetadata class to support multiple sources of location and object metadata.
• split the example_location_data.yaml and example_object_data.yaml files into separate files to simulate scenarios with multiple sources of metadata.
• tested the functionality using the demo.py script with various test worlds specified in form of YAML files in data directory,

Note: Test cases have not been updated yet to reflect the new changes. Will do if this proof-of-concept is okay.