Drop weighty dependencies to keep subsequent libraries light

[kenotron]

Currently, the bulk of the dependencies come from the various lock file api's. They amount to nothing but two kinds of things:

1. finding the right lock file with a find-up style convention
2. parsing yaml
3. stuffing the info obtained into a in-memory collection

I believe we can achieve these with much fewer dependencies so this library isn't so heavy

[kenotron]

#41 alleviates the problem here, but we still don't really use lockfile implementations much other than just reading the yaml file. We honestly should be doing it ourselves with no deps to make it a faster installation process

[ecraig12345]

git-url-parse contributes a substantial set of deps too. It's only used by getRepositoryName (used by getDefaultRemote and getDefaultRemoteBranch), so possibly we could put those utilities in a separate package. Or replace git-url-parse with a custom URL parsing implementation that only extracts the org, owner, and repo since that's all we care about, and we already have to do some custom parsing to work around bugs in git-url-parse.