[https://github.com/tracim/tracim/issues/801] btn to create content or workspace is now disabled if name is empty

frontend_lib/src/component/CardPopup/CardPopupCreateContent.jsx

                   color: '#fdfdfd'
                 }
               }}
+              disabled={!props.contentName || props.contentName.length === 0}
             >
               {props.btnValidateLabel}
             </button>

frontend_lib/src/component/CardPopup/CardPopupCreateContent.styl

         display flex
         justify-content flex-end
         cursor pointer
+        &:disabled
+          cursor not-allowed