Add support for offline work

Currently WinGIN requires online connection to gin.g-node.org during app start and also checks new versions during start up. So user is unable to mount directories and work with files while offline.

Start by tracing the app-start connection to gin.g-node.org and the startup version check; the payload does not name specific files or tests. Done means users can mount directories and work with files offline, while version checking no longer prevents startup without a network connection.

Written by the indexing model from the issue text.