Best practices around exporting/import backend

I'm building a project and the number of custom resources are growing. Most/all examples show custom resources added to `backend.ts`, and I wonder what the best approach would be if I were to extract resources into separate files. My question is mainly on how backend should be handled.

E.g. if I have a custom RestAPI construct, should I be doing this
```
new RestAPI(restApiStack, 'rest-api', {
functions: {
createCustomer: backend.createCustomerHandler.resources.lambda,
createEmployee: backend.createEmployeeHandler.resources.lambda,
},
});

vs

just importing backend from within the RestApi construct? Not sure if exporting backend would result in circular dependencies from a CDK perspective.

Start with the examples that place custom resources in backend.ts and inspect how the RestAPI construct receives the handler resources. Compare the two organization patterns described in the issue, then document a decided recommendation for extracting resources and handling imports, including whether circular dependencies are a concern.

Written by the indexing model from the issue text.