Add x509-limbo patch and reporting tool

[skmcgrail]

Description of changes:

Describe AWS-LC’s current behavior and how your code changes that behavior. If there are no issues this pr is resolving, explain why this change is necessary.

Call-outs:

• The majority of the x509-limbo patch is a 1-1 copy of the code from the openssl harness code from that repository. It just has a very limited set of changes to make it compatible with AWS-LC. I'd suggest not wasting your effort into reviewing that code specifically.
• The Go reporting tool and patch will be built and tested in this PR, but we won't be producing the report output and capturing it / diffing it with the tool until a follow-up PR. I've mostly broken this up to alleviate a large code review for everyone.
• My current intention is to wire this up into a separate CodeBuild project similar to fuzzing. But for now (since that requires CDK work etc), I have wired-up some simple verification of the patching and the reporting tool into the existing Linux CodeBuild project GitHub Actions CI. This is only temporary.

Testing:

• I've added plenty of testing to the Go program itself for the functionality the CLI tool relies on for how to produce the reports.
• Verified the actual CLI commands locally as well.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.75%. Comparing base (39b3fae) to head (a7701e2).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2049   +/-   ##
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  Coverage   78.75%   78.75%           
=======================================
  Files         598      598           
  Lines      103650   103650           
  Branches    14718    14720    +2     
=======================================
  Hits        81633    81633           
+ Misses      21366    21365    -1     
- Partials      651      652    +1     

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[justsmth]

I had an issue with the script failing when the dev workspace already has a "build" directory. Otherwise, I just have some nit-picks.

[justsmth]

I also noticed this error message.

/bin/sh: 1: [[: not found

I suspect that the Makefile's verify-aws-lc-source target is not working as expected:

.PHONY: verify-aws-lc-source
verify-aws-lc-source:
	@if [[ -z "${AWS_LC_SRC_DIR}" ]]; then \
		echo "AWS_LC_SRC_DIR environment variable is missing and is required to specify AWS-LC source location" && false; \
	fi

[andrewhop]

Is it common to use makefile with go code? Or is this a x509-limbo specific thing?

[skmcgrail]

I don't have a data source to point towards, but just from experience it tends to be the go to tool to automate multiple actions for invoking, testing, vetting, etc a Go application. The Go compiler itself does a lot of the leg work when you invoke the build sub-command to slurp up the appropriate files etc. Since Make tends to be readily available it tends to be an obvious choice.