feat: subdocument rest api

@valmy check this out, give your feedback

API should be self explanatory, but there are several delete options, you can look at the tests https://github.com/chopachom/kabam-plugin-rest/commit/6bcfe878cd277b6c141ce143f7018b27b5e47e08#diff-7a2735ccaa2e1eaa80384e16dd95d5e2R210