Ability to customize token name / rename `token` to `ably-token`

[sacOO7]

• Currently, there is a popular laravel-jwt-library => jwt-auth that uses token as a default key name.
• For a given auth request, laravel-broadcaster responds with jwt-token containing channel claims. Client resends it for next request. This is used by server to check for existing channel claims and if token can be upgraded.
• The main issue here is token-key name sent by client in the payload. As per comment https://github.com/ably-forks/laravel-echo/issues/36#issuecomment-2151503954, there is a need to modify this token name.

[sacOO7]

Current token name is token. I recommend to rename it to ably-token. There is no need to provide customization since it doesn't serve any utility as such !