Remove old date picker and misc dependencies

package.json

resources/frontend_client/app/css/external/datepicker.css

...es/frontend_client/app/query_builder/date_filter.react.js

resources/frontend_client/app/query_builder/popover.react.js

...nd_client/app/query_builder/popover_with_trigger.react.js

...es/frontend_client/app/query_builder/sort_widget.react.js

resources/frontend_client/vendor.css

webpack.config.js