insertChannelAsync function
InsertChannel inserts a single channel to dst (coi is 0-based index) (it replaces channel i with another in dst).
For further details, please see: https://docs.opencv.org/master/d2/de8/group__core__array.html#ga1d4bd886d35b00ec0b764cb4ce6eb515
Implementation
Future<Mat> insertChannelAsync(InputArray src, InputOutputArray dst, int coi) async => cvRunAsync0(
(callback) => cffi.core_InsertChannel_Async(src.ref, dst.ref, coi, callback),
(c) => c.complete(dst),
);