Break up aws json protocol tests

This breaks up the aws json protocol test operations into their own
files. This helps a bit to make them easier to read, though the
kitchen sink operation being so big is not helpful in that regard.

smithy-aws-protocol-tests/model/awsJson1_1/empty-operation.smithy

@@ -0,0 +1,42 @@
+$version: "1.0"
+
+namespace aws.protocoltests.json
+
+use aws.protocols#awsJson1_1
+use smithy.test#httpRequestTests
+use smithy.test#httpResponseTests
+
+@httpRequestTests([
+    {
+        id: "sends_requests_to_slash",
+        protocol: awsJson1_1,
+        documentation: "Sends requests to /",
+        method: "POST",
+        uri: "/",
+    },
+    {
+        id: "includes_x_amz_target_and_content_type",
+        protocol: awsJson1_1,
+        documentation: "Includes X-Amz-Target header and Content-Type",
+        headers: {
+            "Content-Type": "application/x-amz-json-1.1",
+            "X-Amz-Target": "JsonProtocol.EmptyOperation",
+        },
+        method: "POST",
+        uri: "/",
+    },
+])
+@httpResponseTests([
+    {
+        id: "handles_empty_output_shape",
+        protocol: awsJson1_1,
+        documentation: "Handles empty output shapes",
+        body: "{}",
+        bodyMediaType: "application/json",
+        headers: {
+            "Content-Type": "application/x-amz-json-1.1",
+        },
+        code: 200,
+    },
+])
+operation EmptyOperation {}