Add support for passing babelOptions to OptionsManager#init

[TuckerWhitehouse]

Taking the minimal approach to option 4 here #89 (comment)

My specific use case is to support passing rootMode: 'upward-optional'.

[tleunen]

Thank you @TuckerWhitehouse. I always appreciate contributions :)
It seems there are very small linting issues, but otherwise the changes look ok. I'm not always happy with adding new options, but if it helps some users, why not. But I wonder if that could be taken from the babel config instead of having to redefine something here? Or maybe I don't fully understand the usecase here

[TuckerWhitehouse]

Hey @tleunen - So by default, babel will the current working directory as the root, but this setting instructs babel to search upward for a babel.config.js file which is useful in monorepos. The babel docs probably do a better job explaining it than I can :D https://babeljs.io/docs/en/options#rootmode

[codecov]

Codecov Report

Merging #113 into master will increase coverage by 0.09%.
The diff coverage is 100.00%.

Impacted Files	Coverage Δ
src/index.js	94.73% <100.00%> (+0.09%)	⬆️

[tleunen]

All good, thank you @TuckerWhitehouse :)

[jcole356]

Looks like this has not been released? Any plans for a new release with this change?

[tleunen]

Oh I thought I had did one. Sorry. Will do now