Support noFrozenLockfile options

[tgroutars]

What did you implement:

We have a monorepo with several serverless packages. Given the way we do CI and the way lerna deals with lockfiles, we actually don't need and don't have an up to date yarn.lock, but for our usecase it doesn't really matter.

This adds the option noFrozenLockfile to packagerOptions, allowing to run yarn install without the --no-frozen-lockfile option. This is as suggested in this comment #369 (comment)

I also fixed the documentation for ignoreScripts in the README, which mentioned a default value of true when it is in fact false

How did you implement it:

Added the option in the install function in yarn.js

How can we verify it:

I added tests to make sure the option was omitted when using noFrozenLockfile

Todos:

• Write tests
• Write documentation
• Fix linting errors
• Make sure code coverage hasn't dropped
• Provide verification config / commands / resources
• Enable "Allow edits from maintainers" for this PR
• Update the messages below

Is this ready for review?: YES
Is it a breaking change?: NO

[tgroutars]

@j0k3r Still nothing in the sidebar to allow edit from maintainers 🤔
Is that maybe a beta feature?

[j0k3r]

I think the problem is that your fork is made from an organization and that feature isn't supported.
isaacs/github#1681

Any chance to create the PR from your own account? Or just fix the small conflicts and it'll be fine :)

[tgroutars]

Ah makes sense, I'll open it from my personal account. Don't want to mess up anything 😅