Support encrypted channels

[sacOO7]

• Echo is mainly designed around Pusher real-time model for client and server.
• Pusher natively supports encrypted channels as per https://pusher.com/docs/channels/using_channels/encrypted-channels/.
• Ably also supports encryption for payload https://ably.com/docs/realtime/encryption.
• The secret key should be distributed to private and presence channels, right next to the ably-capability key, look at first feature - modify channel capability.
• Though, encryption works a bit differently in ably, it can be implemented at a certain point.
• This feature is not yet explicitly requested by users but can be prioritized once the requirement comes.

[sync-by-unito]

➤ Automation for Jira commented:

The link to the corresponding Jira issue is https://ably.atlassian.net/browse/SDK-3652