Add a new (experimental) function write_license_note

[eitsupi]

Close #236

[eitsupi]

Now that the tests are working properly, I think you can merge this.

[eitsupi]

Replacement by cargo metadata failed, it seems that cargo license is still necessary.
However, by using cargo metadata, RcppTOML dependency could be removed.

[Ilia-Kosenkov]

Will there be any benefit to storing license info in a tibble and then mutating it rather than working over disconnected lists?

[eitsupi]

Thanks for the review. I updated.

Will there be any benefit to storing license info in a tibble and then mutating it rather than working over disconnected lists?

cargo-license can also output data as tsv instead of json, but I think additional packages like readr or data.table would be needed to read it on the R side.
Here, I parse json and handle lists with the same structure as json, eliminating the need to depend on those packages.

[Ilia-Kosenkov]

LGTM, a couple of wording improvements here and there.

[CGMossa]

LGTM as well.. I of courses waited until @Ilia-Kosenkov did all the work. But atleast i've skimmed it!

[JosiahParry]

Just a singular typo. Otherwise looks lovely.