This is the same as 097db85e297aba8b4b3f0ddabcddf8a03b5482c0 for the
lockscreen.
The clock so far was manually positioned in a hard coded way which could
result in the clock not being visible.
This changes the layouting of the clock to use a ColumnLayout, with
spacer elements to ensure that the clock stays visible. It is possible
that the position of the clock now does no longer fully reflects the
ideas of the VDG.