No convenient way of rebasing AudioData timestamp

audioData.timestamp is immutable, by design. There is however no convenient way of creating a new AudioData object with a different timestamp. Currently, users have to copy out data (plane by plane) and pass in the same sampleRate, numberofFrames, numberOfChannels parameters.

This issue tracks a proposal to add a new AudioData constructor, which mirrors VideoFrame's "copy constructor".

interface AudioData {
  constructor(AudioData audioData, AudioDataCopyInit init)
  [...]
}

AudioDataCopyInit {
  required long long timestamp;  // microseconds
}

The new constructor would copy all the data and metadata from the passed in audioData, and replace the original timestamp with the one passed in the AudioDataCopyInit.

Start by reviewing the AudioData constructor and the existing VideoFrame copy-constructor pattern described in the issue. Determine how the proposed AudioDataCopyInit should preserve data and metadata while replacing only the timestamp. Done means the proposal is specified consistently with the existing WebCodecs API.