fix php version in kweb config (#357)

* fix php version in kweb config
* include webapp kweb config only in the webapp container build
* add workaround for https://jira.kopano.io/browse/KW-3398 for oidc

webapp/Dockerfile

@@ -71,6 +71,7 @@ RUN mkdir -p /tmp/webapp/ && \
         ln -s /tmp/webapp/"$(basename "$i")" "$i"; \
     done
 
+COPY kweb.cfg /etc/kweb.cfg
 COPY start.sh /kopano/start.sh
 COPY goss* /goss/