use path parameter for channel name

[bluebrown]

use path parameter for channel name

[Archisman-Mridha]

Issue description

Currently webhook events are received at /events and the channel name is present as a query parameter in the URL.

Query parameters are generally used for optional parameters. So, we want to switch to path parameters.

Webhook events should be received at /events/<channel-name>.So, the channel name will be present as path parameter instead.

Note

The query parameter option will still be available for backwards compatibility, but it'll be marked as deprecated.