Implement Chemical Subclass Extending the Node Class

[yunchae-kim]

Building on the Node class (referenced in Issue-#102), we also need a Chemical subclass. This will help handle the specific data types we use in Comptox AI.

Objectives:

1. Specialization: While the Node class provides a generic interface, the Chemical subclass will be tailored to handle attributes and methods specific to chemical data.
2. Integration: Ensure the Chemical subclass can seamlessly interact with the Comptox AI Neo4j database and pull chemical-specific data.

Key Tasks:

• Define attributes unique to Chemical nodes.
• Integrate with current chemical handling methods, such as fetch_chemicals, to retrieve and process chemical data from the database.
• Ensure the Chemical class is able to parse and present data in a Python-friendly format.