Decide on correct naming for logger types and properties

[lawrence-forooghian]

At the moment, we have an existing type ARTLog, which is set as the ARTClientOptions’s logHandler property (whose naming comes from the feature spec). And then internally in the codebase it's often assigned to a logger property.

So, a couple of things:

1. What is the correct class / type name? *Log or *Logger or *LogHandler?
2. Once we decide that, then align the property names to match.

(Created from #1616 (comment))

┆Issue is synchronized with this Jira Task by Unito

[sync-by-unito]

➤ Automation for Jira commented:

The link to the corresponding Jira issue is https://ably.atlassian.net/browse/SDK-3520