rebase and update IDL changes

[Sapples]

Based on: EDX-180
Follow up/replacement from old PR to be closed: #5

• Add changes as per #1427
• Add changes as per #1444
• Add changes as per #1453
• Add changes as per #1460 (No changes to IDL)
• Add changes as per #1462
• Add changes as per #1464
• Add changes as per #1465

[m-hulbert]

Quite a few comments on this one, sorry. Happy to walk through it with you though if that would help.

In addition there's some things that were missing from the linked PRs, as well as one change I think is in a separate PR that wasn't listed in the original JIRA but should be covered as part of this:

• Update Rest and Realtime to RestClient and RealtimeClient and all associated links as per https://github.com/ably/docs/pull/1459/files. Be aware of any mention of "REST client" or "Realtime client" as well as any links to those classes.
• Auth should have a tokenDetails property as per https://github.com/ably/docs/pull/1462/files
• I think the description for extras in the Message class needs to be updated due to the message interactions implementation.
• ably/docs#1499 added clientId to message filters. This needs to be added.
• The cipher property needs updating in ChannelOptions as per ably/docs#1464
• I made a comment about making deprecated properties consistent in a few places, so happy to help with this too!

[m-hulbert]

• All the references to Stats.* objects should be in backticks.
• I think the stats descriptions need checking over again. I think the descriptions have been carried through for them all about the "count and byte value of messages", however this can be quite nested. Taking Stats.MessageDirections as an example, two of the properties are Stats.MessageTraffic and the other is Stats.MessageTypes yet they all have the same description. This applies to all the stats classes.

[m-hulbert]

The cipher property needs updating in ChannelOptions as per ably/docs#1464 still please.

[m-hulbert]

Just a couple of styling points and a few stats suggestions!

[m-hulbert]

👍