utils: Sanitize name resolution failures and wrong server values
utils: Sanitize name resolution failures and wrong server values

Other than SOUP_STATUS_UNAUTHORIZED, these are the more common
failures encountered by a user. The name resolution failures are quite
obvious, but failures arising due to subtle mistakes in the server
string entered by the user are harder to detect. In my limited testing,
failures to find the WebDAV endpoint either led to
SOUP_STATUS_INTERNAL_SERVER_ERROR or SOUP_STATUS_NOT_FOUND.

Note that even though SoupMessage:reason_phrase gets a localized error
string from glib-networking in the case of name resolution failures,
the documentation (see soup_status_get_phrase) explicitly says
otherwise and advises against presenting them to the user. So, let's
not get into uncharted waters.

https://bugzilla.gnome.org/show_bug.cgi?id=755168

ritzk/gnome-online-accounts,ritzk/gnome-online-accounts,ritzk/gnome-online-accounts