[9.x] Add environment variables for new AblyBroadcaster

[owenpearson]

Note: this PR is one of four parallel pull requests to add first class support for Ably to Laravel. Please find the other PRs here:

• laravel/docs#8120
• laravel/framework#43685
• laravel/echo#351

Background: the current Ably broadcaster uses the Pusher JavaScript SDK and the documentation instructs users to use Ably with the Pusher compatibility mode enabled. We’ve received a lot of feedback that various features of the Ably Laravel integration don’t work as expected, often caused by the fact that there’s a dependency on the Pusher JavaScript SDK which we have no control over. This collection of PRs adds a new broadcaster which uses the ably-js SDK which means that we can ensure that the Ably broadcaster will remain stable. We are more than happy to take feedback and answer any questions about the work presented here :)

Adds example environment variables to .env.example for the new AblyBroadcaster and references them in broadcasting.php.

[oseiasPlenoIMOB]

Hello @owenpearson, I don't know if this is your problem, but in my case I used the lib wrench to create a Pure WebSocket communication in PHP using laravel. Hope this helps! https://github.com/varspool/Wrench

[sacOO7]

Hello @owenpearson, I don't know if this is your problem, but in my case I used the lib wrench to create a Pure WebSocket communication in PHP using laravel. Hope this helps! https://github.com/varspool/Wrench

Hi @oseiasPlenoIMOB , this is not related to the PR. You should read more about https://laravel.com/docs/9.x/broadcasting