The deployment was incomplete. Fix it by:
* Building the dependent qtgrpc_chat_client_proto library as
a static library
* Add the server directory path for reading credentials universally
Amends: cb35d20adb.
Fixes: QTBUG-134266
Pick-to: 6.9.0 6.9 6.8.3 6.8
Change-Id: I0666c445fbce159436c5b084ffd77d4191e04213
Reviewed-by: Alexey Edelev <alexey.edelev@qt.io>