[azopenai] Implement UnmarshalJSON method for custom types (#22133)

A UnmarshalJSON method has been added to the ChatCompletionsToolChoice and ChatRequestUserMessageContent structs. These implementations allow the structs to satisfy the json.Unmarshaller interface, enabling them to decode JSON directly into their respective types.

sdk/ai/azopenai/custom_client.go

@@ -327,3 +327,8 @@ func NewChatRequestUserMessageContent[T string | []ChatCompletionRequestMessageC
 func (c ChatRequestUserMessageContent) MarshalJSON() ([]byte, error) {
 	return json.Marshal(c.value)
 }
+
+// UnmarshalJSON implements the json.Unmarshaller interface for type ChatRequestUserMessageContent.
+func (c *ChatRequestUserMessageContent) UnmarshalJSON(data []byte) error {
+	return json.Unmarshal(data, &c.value)
+}

sdk/ai/azopenai/custom_models.go

@@ -185,3 +185,8 @@ func (tf ChatCompletionsToolChoiceFunction) MarshalJSON() ([]byte, error) {
 func (tc ChatCompletionsToolChoice) MarshalJSON() ([]byte, error) {
 	return json.Marshal(tc.value)
 }
+
+// UnmarshalJSON implements the json.Unmarshaller interface for type ChatCompletionsToolChoice.
+func (tc *ChatCompletionsToolChoice) UnmarshalJSON(data []byte) error {
+	return json.Unmarshal(data, &tc.value)
+}