WindowsBuild: Install Gajim as a python package

See merge request !118

Make gajim a python module

See merge request !106

to work around the issue that the gajim module cannot be found

A jid can contain characters that are not allowed in an action name.
This creates a unique UUID4 for each MessageControl and uses it as
action name instead.

We can reuse the UUID for other actions that belong to the
MessageControl

Fixes #8636

It seems to be important to let all widgets realize and then
hide the ones we dont want to show, instead of not showing them
in the first place.

This reverts commit b9c363e9.

receive() returns bytes, not str

rework password interface. Fixes #8347

Closes #8347

See merge request !117