[BUG] license validator does not match arborist

[wraithgar]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

In arborist's inventory class it does its own attempts to normalize/account for license/licence but it ALSO is looking for licenses/licences, which @npmcli/package-json does not appear to to

https://github.com/npm/cli/blob/8ded848b099297a12a81ec008d6229f3ad3494a6/workspaces/arborist/lib/inventory.js#L62-L73

Expected Behavior

See if we can safely consolidate this normalization into this module, or at least see if we want to normalize the array/plural version.