Expose whether comment author is also video creator through comments API

[TobiGr]

Describe the problem to be solved

Currently, the only option to check whether the comment author is also the video creator is to fetch the video details. This is done for example here in the client. In some cases this is not wanted due to additional requests being necessary, e.g. when handling comments separately (as done in NewPipeExtractor).

Describe the solution you would like

Expose whether a comment creator is the video creator with a new field in comment objects or their dedicated author objects for all comments GET requests. This field could be named isVideoAuthor or something similar.