Merge branch 'bug/connection-to-calyx.net-fails-and-app-crashes-#4550' into develop
Merge remote-tracking branch 'parmegv/bug/app-crashes-if-there-is-no-anonymous-certificate-#5310' into develop
Back button while setting up a provider works

It stops the process, you can restart it as usual, but if you press back
again you quit the app because there is no chosen provider.
Refactored.
Pressing back always returns to CW.

This commit fixes a problem when back was pressed when the vpn certificate had been already downloaded (2/3 of the progressbar).