chore(goimports): change imports-check from go list to find

The previous imports-check target uses `go list` to find code to scan.
The problem is that `go list` produces a listing of directories to input
into goimports.

/a/b/c
/a/b/c/d
/a/b/c/e ---> example we want to exclude

In the example listing above, we want to exclude `e`. That was previously
done by excluding `e` via a `grep -v` command that followed `go list`.
The result is that the path with `e` on the end is excluded, but `/a/b/c`
is still scanned causing the excluded path to get scanned anyway. This
commit swaps all this out for a find command that excludes the paths and
returns filenames as input, not directories.

Makefile

@@ -148,7 +148,7 @@ fmt-check: ## Lists formatting issues
 
 .PHONY: imports-check
 imports-check: ## Lists imports issues
-	@test -z $(shell goimports -l $(shell go list -f {{.Dir}} ./... | grep -v proto))
+	@test -z $(shell goimports -l $(shell find . -type f -name '*.go' -not -path './vendor/*' -not -path './cli/cdk/go/proto/*'))
 
 .PHONY: run-api-example
 run-api-example: ## Run an API example like 'make run-api-example example=api/_examples/active-containers/main.go'