Support to extend SidecarBody subclass

[binsee]

In use, I wrote a sidecar subclass for use in a formal environment.

@Sidecar('chatbox')
class Test extends SidecarBody {

  @Call(0x42)
  @RetType('pointer', 'Utf8String')
  testMethod(
    @ParamType('pointer', 'Utf8String') content: string,
    @ParamType('int') n: number
  ): Promise<string> {
    return Ret(content, n)
  }

  @Hook(agentTarget('agentVar'))
  hookMethod(@ParamType('int') n: number) {
    return Ret(n)
  }
}

But in development, I need to extend an additional class for isolation use, which needs to inherit the previous class.

@Sidecar('chatbox')
class Test2 extends Test {

  @Call(exportTarget('exportNameTest', 'moduleNameTest'))
  @RetType('pointer', 'Int')
  anotherCall(@ParamType('pointer', 'Int') i: number): Promise<number> {
    return Ret(i)
  }
}

However, currently sidecar cannot obtain the function information declared in the parent class. In order to solve the above requirements, this problem needs to be solved.