* [WEB] add UI for transcription

* add analytics event for button, do not use global APP object

* use props instead of state, use local conference to kick participant

* put imports in alphabetical order

* add translation for TranscribingLabel

* fix merge conflict

* add closed caption button

* purge OverFlowMenuItem which starts and stops Transcription

* readd closed caption icon and fix small issues due to purge

* delete unused icon in _font.scss

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.