Support *string type for openapi

Kubernete CRD Defined:
```golang
type Test struct {
	// +kubebuilder:validation:Minlength=1
	// +optional
	Name *string `json:"name,omitempty"`
	// +required
	ID   int      `json:"id"`
}
```

call `BuildOpenAPISpecFromRoutes` error
```bash
non-body Restful parameter type should be a simple type, but got : *string
```

