chore: implement method to validate suspicious packages for malicious…

[Yao-Wen-Chang]

This PR refers to issue #810.

This PR implements the validator to confirm malware on PyPI. We analyze the data flow by walking through the AST and finding out the actual value of the variable.

For example:

requests.get(malicious_endpoint)
malicious_endpoint = "https://malicious.com"

The new method should be able to detect the https://malicious.com. Furthermore, we will analyze the historical malware data to define the suspicious pattern as a .yaml.

The suspicious_setup heuristic will be removed since it overlaps with our new method.

Following are the tasks for implementing this method:

• Analyze the historical malware and define the malicious pattern in .yaml
• Remove suspicious_setup heuristic
• Implement the method to analyze the data flow
• Provide unit tests
• Test the method on the latest packages on PyPI to ensure the detector is more accurate