per-user installation context on Windows

Hi,

In the setup wizard of LibreOffice one can choose between installing
LibreOffice for all users (per-machine context), and installing
LibreOffice for the currently logged in user (per-user context). I
could not find a good reason to keep this choice on the UI.

Installation works from administrator account only. Non-privileged
users cannot install LibreOffice even in per-user context. They can
use portable versions for example. Help packs are installed in
per-machine context unconditionally.

If we removed this choice from the UI along with the useless User
name/Organization prompts (see fdo#46559), we could have one screen
less in the installation wizard. If someone is insisting on installing
LibreOffice in per-user context, the ALLUSERS="" property can be
passed in the command line (also for help packs).

Please let me know, if you disagree.

Thanks,
Andras