[MM-26832] don't show the window until it is ready (#1345)
[MM-26832] don't show the window until it is ready (#1345)

* [MM-26832] don't show the window until it is ready

* [MM-26832] allow the app to still paint itself while initially hidden

* fix tests, ensure it appears if not using silent mode
mattermost/desktop,mattermost/desktop,mattermost/desktop,mattermost/desktop,mattermost/desktop