fix: support for named typed client exports for files with multiple contacts

[aorumbayev]

#35

Proposed Changes

• Changed typed client generation to account for multiple contract classes in single contract.py file
• Additionally simplifying helpers by removing some redundant files and marking the folder as private (by python conventions) to signify that there is no need to modify those scripts if dev is ok with conventions the template provides
• Adding extra record to code tour to explain helpers folder