refactor: Removed dependency on lodash.keyBy (optimizely#416)

Summary:

Replaced lodash values function with keyBy from js-sdk-utils and added missing functionality. This is part of an effort to remove lodash dependency to reduce bundle size.

Test Plan:
1) Added Unit tests
2) All Unit tests and Full Stack SDK compatibility passed

Author: zashraf1985

packages/optimizely-sdk/lib/utils/fns/index.js

@@ -1,5 +1,5 @@
 /**
- * Copyright 2017, 2019, Optimizely
+ * Copyright 2017, 2019-2020, Optimizely
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,6 +15,7 @@
  */
 var uuid = require('uuid');
 var _isFinite = require('lodash/isFinite');
+var keyBy = require('@optimizely/js-sdk-utils').keyBy;
 var MAX_NUMBER_LIMIT = Math.pow(2, 53);
 
 module.exports = {
@@ -27,7 +28,12 @@ module.exports = {
   isFinite: function(number) {
     return _isFinite(number) && Math.abs(number) <= MAX_NUMBER_LIMIT;
   },
-  keyBy: require('lodash/keyBy'),
+  keyBy: function(arr, key) {
+    if (!arr) return {};
+    return keyBy(arr, function(item) {
+      return item[key];
+    });
+  },
   forEach: require('lodash/forEach'),
   forOwn: require('lodash/forOwn'),
   uuid: function() {

packages/optimizely-sdk/lib/utils/fns/index.tests.js

@@ -37,6 +37,35 @@ describe('lib/utils/fns', function() {
         assert.isTrue(fns.isFinite(-Math.pow(2, 53)));
       });
     });
+
+    describe('keyBy', function() {
+      it('should return correct object when a key is provided', function() {
+        var arr = [
+          { key1: 'row1', key2: 'key2row1' },
+          { key1: 'row2', key2: 'key2row2' },
+          { key1: 'row3', key2: 'key2row3' },
+          { key1: 'row4', key2: 'key2row4' },
+        ];
+
+        var obj = fns.keyBy(arr, 'key1');
+
+        assert.deepEqual(obj, {
+          row1: { key1: 'row1', key2: 'key2row1' },
+          row2: { key1: 'row2', key2: 'key2row2' },
+          row3: { key1: 'row3', key2: 'key2row3' },
+          row4: { key1: 'row4', key2: 'key2row4' }
+        });
+      });
+      
+      it('should return empty object when first argument is null or undefined', function() {
+        var obj = fns.keyBy(null, 'key1');
+        assert.isEmpty(obj);
+
+        obj = fns.keyBy(undefined, 'key1');
+        assert.isEmpty(obj);
+        });
+    });
+    
     describe('isNumber', function() {
       it('should return true in case of number', function() {
         assert.isTrue(fns.isNumber(3));