feat: add groupValuesOnKey to namespace

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---

Author: kgryte

lib/node_modules/@stdlib/array/base/lib/index.js

@@ -1062,6 +1062,15 @@ setReadOnly( ns, 'groupValues', require( '@stdlib/array/base/group-values' ) );
 */
 setReadOnly( ns, 'groupValuesBy', require( '@stdlib/array/base/group-values-by' ) );
 
+/**
+* @name groupValuesOnKey
+* @memberof ns
+* @readonly
+* @type {Function}
+* @see {@link module:@stdlib/array/base/group-values-on-key}
+*/
+setReadOnly( ns, 'groupValuesOnKey', require( '@stdlib/array/base/group-values-on-key' ) );
+
 /**
 * @name incrspace
 * @memberof ns