Adding plugin.Driver mocks (#17807)

This is needed for plugin clients to mock tests.

```release-note
NONE
```

Makefile

@@ -301,6 +301,7 @@ plugin-mocks: ## Creates mock files for plugins.
 	$(GOBIN)/mockery -dir plugin -name API -output plugin/plugintest -outpkg plugintest -case underscore -note 'Regenerate this file using `make plugin-mocks`.'
 	$(GOBIN)/mockery -dir plugin -name Hooks -output plugin/plugintest -outpkg plugintest -case underscore -note 'Regenerate this file using `make plugin-mocks`.'
 	$(GOBIN)/mockery -dir plugin -name Helpers -output plugin/plugintest -outpkg plugintest -case underscore -note 'Regenerate this file using `make plugin-mocks`.'
+	$(GOBIN)/mockery -dir plugin -name Driver -output plugin/plugintest -outpkg plugintest -case underscore -note 'Regenerate this file using `make plugin-mocks`.'
 
 einterfaces-mocks: ## Creates mock files for einterfaces.
 	$(GO) get -modfile=go.tools.mod github.com/vektra/mockery/...