sidebar: Build with cloudproviders support
The cloudproviders integration used to be part of GTK 3 version, but
it is not part of GTK 4 version. This is because the sidebar codes
are now part of Nautilus codebase and HAVE_CLOUDPROVIDERS
is never
set. Let's allow to build with cloudproviders support again.
Related: #2392 (closed)
Edited by Ondrej Holy