feat(appsec): enable request blocking

[florentinl]

What does this PR do?

This PR enables Appsec to block request if they are deemed dangerous by the in-app WAF.

There are three cases:

• Blocking before executing the wrapped function, after calling asm_start_request
• Blocking during execution of the wrapped function, by raising a BlockingException
• Blocking after execution of the function, after calling asm_start_response

Motivation

Expand the capabilities of Appsec inside the datadog-lambda-python layer.

Testing Guidelines

I added unit tests to both test_asm.py and test_wrapper.py to ensure requests are blocked only if necessary and at the right stage.

Integration tests will be run as part of the system-test, APPSEC_BLOCKING scenario.

Types of Changes

• Bug fix
• New feature
• Breaking change
• Misc (docs, refactoring, dependency upgrade, etc.)

Check all that apply

• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
• This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• This PR impacts documentation, and it has been updated (or a ticket has been logged)
• This PR's changes are covered by the automated tests
• This PR collects user input/sensitive content into Datadog
• This PR passes the integration tests (ask a Datadog member to run the tests)

[purple4reina]

Here's one way to better handle this.

Suggested change

	try:
	encoded_query = urllib.parse.urlencode(parsed_query, doseq=True)
	except Exception:
	pass
	raw_uri += "?" + encoded_query # type: ignore
	try:
	encoded_query = urllib.parse.urlencode(parsed_query, doseq=True)
	raw_uri += "?" + encoded_query # type: ignore
	except Exception:
	pass

[purple4reina]

One small issue to fix.