Update cdk.template.json to include *.go files.

The current behavior for `cdk deploy` is to run `go run cdk.go`.

This requires all of the code to be in the named file.

Switching it to `go run .` will allow additional files to be included.
As the cdk stack becomes more complex, breaking out different props into different files makes the code easier to maintain.

packages/aws-cdk/lib/init-templates/app/go/cdk.template.json

@@ -1,5 +1,5 @@
 {
-  "app": "go mod download && go run %name%.go",
+  "app": "go mod download && go run .",
   "watch": {
     "include": ["**"],
     "exclude": [