fix: infix operation handling

[brech1]

Description

This PR aims to fix the multi term infix operations processing. We're now able to process these operations and create the corresponding gates if necessary.

Changes

• Remove every tuple return and replace with Result
• Implement Result return on functions without return, in order to remove unwraps and improve error handling.
• Update execute_expression to return a value of the processed expression.
• Update execute_infix_op to run the operation and return the result.
• Fix substitution handling in execute_statement.
• Remove unused variable name argument from execute_expression and traverse_expression.
• Implement ProgramError.
• Update runtime logs.
• Implement declare_auto_signal in the runtime.