[ERC Registry] Add mechanism to evaluate STARTING_POINT variable

[quiet-node]

Problem

The STARTING_POINT environment variable, as outlined in the design document, determines the starting point for the indexing process, allowing the indexer to avoid re-indexing the entire network. The STARTING_POINT can take one of the following forms:

• Contract ID
• Contract Address
• next pointer

Solution

Implement a utility function to evaluate the STARTING_POINT variable, ensuring the indexer operates as intended and aligns with the defined starting point.