Summary:
Currently the schema only allows to exclude a single platform (iOS OR Android). There are cases where we need to exclude multiple. This change converts the previous `excludePlatform` string property into an `excludePlatforms` array.
Changelog:
[Internal][Changed] - Added support to exclude multiple platforms in Codegen.
Reviewed By: sammy-SC
Differential Revision: D21426950
fbshipit-source-id: eff36ffa207109274794b4b300bf6313f8286161
João Vieira