Add support for RSN3a, c (Channels)

[AndyNicks]

Add support for the following requirements: RSN3a, c

As stated at https://docs.ably.io/client-lib-development-guide/features/#RSN3c https://docs.ably.io/client-lib-development-guide/features/#RSN3a

see details https://github.com/ably/docs/blob/main/content/client-lib-development-guide/versions/features-1-1__1-2.diff

Acceptance Criteria:

Implement the support for the requirements above

Update the spreadsheet

┆Issue is synchronized with this Jira Story by Unito

[ably-sync-bot]

➤ Nikita Misharin commented:

This is done and the spreadsheet is also updated

[ably-sync-bot]

➤ Nikita Misharin commented:

My bad, actually it was not done. I understood it only when started to work on ChannelOptions. Reassigning it back to me