Will override email, display name and avatar URL with the values
provided in 'context.user' structure of the JWT token.

Settings will no longer be used to retrieve local display name,
email and avatar URL. Now those values will be obtained from
the /features/base/participants Redux state.

fix(jwt/middleware): use const for default name

fix: wrong default display name on web

ref(base/participants): remove getDisplayName functions

ref(jwt): do not accept unknown user fields

Make 'Add jwt module to react' work on mobile.

As an intermediate step on the path to merging jitsi-meet and
jitsi-meet-react, import the whole source code of jitsi-meet-react as it
stands at
2f23d98424
i.e. the lastest master at the time of this import. No modifications are
applied to the imported source code in order to preserve a complete
snapshot of it in the repository of jitsi-meet and, thus, facilitate
comparison later on. Consequently, the source code of jitsi-meet and/or
jitsi-meet-react may not work. For example, jitsi-meet's jshint may be
unable to parse jitsi-meet-react's source code.