Fix Context naming issues with inference contracts

[prakashngit]

1. Reuse vetting, asset, and issuer context from exchange modules for the inference jupyter module, rather than redefining.
2. Renamed the inference specific contexts to prevent overwriting of exchange related contexts
3. With these changes, a single instance of jupyter container can be used to interact with both inference and exchange contracts

[cmickeyb]

supercede by #36