chore(core): update network and prefix properties

[jrriehl]

Proposed Changes

Improve interface for setting network between testnet and mainnet and add prefix attribute.

Linked Issues

[if applicable, add links to issues resolved by this PR]

Types of changes

What type of change does this pull request make (put an x in the boxes that apply)?

• Bug fix (non-breaking change that fixes an issue).
• New feature added (non-breaking change that adds functionality).
• Breaking change (fix or feature that would cause existing functionality to stop working as expected).
• Documentation update.
• Something else (e.g., tests, scripts, example, deployment, infrastructure).

Checklist

Put an x in the boxes that apply:

• I have read the CONTRIBUTING guide
• Checks and tests pass locally

If applicable

• I have added tests that prove my fix is effective or that my feature works
• I have added/updated the documentation (executed the script in python/scripts/generate_api_docs.py)

[Alejandro-Morales]

LGTM