Add a CI step for checking app SDK codegen status (#111528)

* Add a CI step for checking app SDK codegen status

What

This commit adds a CI step for checking the status of code generated
with Grafana App SDK. The step fails if there is a git diff as a result
of the codegen step.

It also updates generated code to make sure we're starting from a
correct state.

Why

This ensures that when the schemas or the SDK version are updated, the
codegen mismatch is caught early at the PR stage.

Signed-off-by: Igor Suleymanov <igor.suleymanov@grafana.com>

* Format generated code

Signed-off-by: Igor Suleymanov <igor.suleymanov@grafana.com>

---------

Signed-off-by: Igor Suleymanov <igor.suleymanov@grafana.com>

Makefile

@@ -173,7 +173,19 @@ gen-cuev2: ## Do all CUE code generation
 APPS_DIRS := ./apps/dashboard ./apps/folder ./apps/alerting/notifications
 
 .PHONY: gen-apps
-gen-apps: ## Generate code for Grafana App SDK apps
+gen-apps: do-gen-apps gofmt ## Generate code for Grafana App SDK apps and run gofmt
+	@if [ -n "$$CODEGEN_VERIFY" ]; then \
+		echo "Verifying generated code is up to date..."; \
+		if ! git diff --quiet; then \
+			echo "Error: Generated apps code is not up to date. Please run 'make gen-apps' to regenerate."; \
+			git diff --name-only; \
+			exit 1; \
+		fi; \
+		echo "Generated apps code is up to date."; \
+	fi
+
+.PHONY: do-gen-apps
+do-gen-apps: ## Generate code for Grafana App SDK apps
 	for dir in $(APPS_DIRS); do \
 		$(MAKE) -C $$dir generate; \
 	done
@@ -388,7 +400,7 @@ lint-go-diff:
 
 .PHONY: gofmt
 gofmt: ## Run gofmt for all Go files.
-	gofmt -s -w .
+	@go list -m -f '{{.Dir}}' | xargs -I{} sh -c 'test ! -f {}/.nolint && echo {}' | xargs gofmt -s -w 2>&1 | grep -v '/pkg/build/' || true
 
 # with disabled SC1071 we are ignored some TCL,Expect `/usr/bin/env expect` scripts
 .PHONY: shellcheck