feat: add simple API tests

src/main/resources/http/create.http

@@ -0,0 +1,7 @@
+POST http://localhost:8080/demo
+Content-Type: application/json
+
+{
+  "name": "hello kotlin",
+  "age": 20
+}

src/main/resources/http/datasource.http

@@ -0,0 +1,2 @@
+GET http://localhost:8080/dataSource
+Content-Type: application/json

src/main/resources/http/findAll.http

@@ -0,0 +1,2 @@
+GET http://localhost:8080/demo
+Content-Type: application/json

src/main/resources/http/findById.http

@@ -0,0 +1,2 @@
+GET http://localhost:8080/demo/1
+Content-Type: application/json