Rate limit github clone calls

[cbrand]

Description

Fixes #139.

Add rate limiting to github clone calls, avoiding issues with github "permission denied" and EOF errors when cloning too many repositories in parallel.

TODOs

Read the Gruntwork contribution guidelines.

• Update the docs.
• Run the relevant tests successfully, including pre-commit checks.
• Ensure any 3rd party code adheres with our license policy or delete this line if its not applicable.
• Include release notes. If this PR is backward incompatible, include a migration guide.

Release Notes

Added

• Rate limiting Github Clone calls to 4 per default, allows being parametrized by the --max-concurrent-clones flag

Migration Guide

None needed

[XavierChanth]

For the reviewers, I was able to build git-xargs and used this build to clone ~80 repos mostly successfully, while the current release was only cloning 1 repo.

[flinn]

@brikis98 @hongil0316 What all is necessary in order to help get these changes merged/published? Asking as we've started to use git-xargs recently and without this feature we'll be very unlikely to proceed in using this tool as we're attempting to use it across ~300+ repositories.

[yogur]

We have 2000+ repos to update and I had to use a script to execute git-xargs in batches of 50 repos to go around repo clone rate-limiting, which somewhat defeats the purpose of batching offered by this tool!

I compiled the changes in this PR and used it. It solved our issue! Would be great if it gets merged soon.

[james03160927]

Sorry for the delay. It seems like some of the tests for repository is failing. Can you make sure those tests pass?

FAIL github.com/gruntwork-io/git-xargs/repository 300.028s

[james03160927]

Friendly ping on this PR.

[cbrand]

@james03160927 Hey I had a chance to take a look and seem to have fixed the unit tests. Please take another look:

?   	github.com/gruntwork-io/git-xargs/common	[no test files]
?   	github.com/gruntwork-io/git-xargs/config	[no test files]
?   	github.com/gruntwork-io/git-xargs/local	[no test files]
?   	github.com/gruntwork-io/git-xargs/mocks	[no test files]
?   	github.com/gruntwork-io/git-xargs/printer	[no test files]
?   	github.com/gruntwork-io/git-xargs/stats	[no test files]
?   	github.com/gruntwork-io/git-xargs/util	[no test files]
ok  	github.com/gruntwork-io/git-xargs	0.488s
ok  	github.com/gruntwork-io/git-xargs/auth	0.223s
ok  	github.com/gruntwork-io/git-xargs/cmd	1.893s
ok  	github.com/gruntwork-io/git-xargs/io	0.680s
ok  	github.com/gruntwork-io/git-xargs/repository	2.154s
ok  	github.com/gruntwork-io/git-xargs/types	1.158s

[james03160927]

LGTM. Passed all the tests.