fix: patch additions honor source key style

When a patch appends a new node, it should honor the key style from the
patch. Prior to this commit, no style was applied, leading to problems
when the key value could be interpreted as a different type based on its
content. For example, "9110" needs quoting to ensure it is seen as a
string in yaml.

kyaml/yaml/merge2/map_test.go

@@ -417,6 +417,47 @@ spec:
       protocol: TCP
     - port: 30901
       targetPort: 30901
+`,
+		mergeOptions: yaml.MergeOptions{
+			ListIncreaseDirection: yaml.MergeOptionsListAppend,
+		},
+	},
+
+	//
+	// Test Case
+	//
+	{description: `Verify key style behavior`,
+		source: `
+kind: Deployment
+spec:
+  source-and-dest: source-and-dest
+  source-only: source-only
+  "source-only-key-double-quoted": source-only
+  source-and-dest-key-style-diff-1: source-and-dest
+  'source-and-dest-key-style-diff-2': source-and-dest
+  "source-and-dest-key-style-diff-3": source-and-dest
+`,
+		dest: `
+kind: Deployment
+spec:
+  source-and-dest: source-and-dest
+  'source-and-dest-key-style-diff-1': source-and-dest
+  "source-and-dest-key-style-diff-2": source-and-dest
+  source-and-dest-key-style-diff-3: source-and-dest
+  dest-only: dest-only
+  'dest-only-key-single-quoted': dest-only 
+`,
+		expected: `
+kind: Deployment
+spec:
+  source-and-dest: source-and-dest
+  'source-and-dest-key-style-diff-1': source-and-dest
+  "source-and-dest-key-style-diff-2": source-and-dest
+  source-and-dest-key-style-diff-3: source-and-dest
+  dest-only: dest-only
+  'dest-only-key-single-quoted': dest-only 
+  source-only: source-only
+  "source-only-key-double-quoted": source-only
 `,
 		mergeOptions: yaml.MergeOptions{
 			ListIncreaseDirection: yaml.MergeOptionsListAppend,