openvidu-browser: Stream.typeOfVideo backwards compatibility fix
openvidu-browser: Stream.typeOfVideo backwards compatibility fix

Stream.typeOfVideo was a string and cannot be changed into an Enum
without breaking some client applications.

However, it is possible for us to start using an Enum internally, and
exporting this property as a union of strings, which is what is
generated by "keyof typeof Enum".

OpenVidu/openvidu,OpenVidu/openvidu,OpenVidu/openvidu,OpenVidu/openvidu,OpenVidu/openvidu,OpenVidu/openvidu