Revert "Client info request: Rename browser field to userAgent"
Revert "Client info request: Rename browser field to userAgent"

This reverts commit 71c75d4253993f04871bc50906b8cb4c70831d1d.

Pushed to the wrong branch.

threema-ch/threema-web,threema-ch/threema-web,threema-ch/threema-web,threema-ch/threema-web,threema-ch/threema-web