xdg-email fails on kde with desktop files #187

This fixes issue #187 (closed)

Variable client below will contain "mail-app.desktop" in some cases.

            local client=$($kreadconfig --file emaildefaults \
                                        --group "PROFILE_$profile" \
                                        --key EmailClient \
                                  | cut -d ' ' -f 1)

Script will now detect those cases and get executable path by calling desktop_file_to_binary like open_gnome3/generic() do.

cc @faure I think this can land

Would be great if we could land this, as a fresh Fedora 35 install is currently broken when using Thunderbird as a mail client under KDE.

merged