[FEATURE] Customer Lambda Gateway Authorizer Scanning

[Josh-Beck]

Describe the feature
AWS Gateway allows a customer authorizer for APIs. Scan this file as part of the vulnerability checks.
Likely, this will involve including the objects in the mapping, extending mappings beyond one file.

Feature Requirements

• Scanner takes in Gateway Authorizer Lambda link (obtained separately, via CLI or new parser implementation)
• Scanner scans this lambda code in conjunction with target lambda function code.
• Results for target lambda function take into account extra validations from authorizer.

Customer/Developer Value Proposition
Create more accurate and extensible results for scanning engine.