fix(napi-derive-backend): should respect origin name for class factory

[richerfu]

Fix generated code for class factory:

example:

use napi_derive::napi;

pub struct QueryEngine {}
 
#[napi(js_name = "QueryEngine")]
pub struct JSQueryEngine {
  engine: QueryEngine,
}
 
#[napi]
impl JSQueryEngine {
  #[napi(factory)]
  pub fn with_initial_count() -> Self {
    JSQueryEngine { engine: QueryEngine {} }
  }
}

export declare class QueryEngine {
  static withInitialCount(): JsQueryEngine
}
export type JSQueryEngine = QueryEngine

should be:

export declare class QueryEngine {
  static withInitialCount(): QueryEngine
}
export type JSQueryEngine = QueryEngine