Demo-app: Add birthday height set option

[HonzaR]

Is your feature request related to a problem? Please describe.

We'd like to have a way to set birthday wallet height in the testing demo-app

Describe the solution you'd like

I'm in favour of implementing this feature in new-ui demo-app. Old-ui could be manually changed only in code, if needed. In the new-ui demo-app it could live on the choose base address screen below the list of possible addresses.

Additional context

As it showed up recently, it will help us in testing and analysing possible troubles.