feat(channels): custom channels

[samuelmasse]

Adds a way to create mappings for any arbitrary string. The channel part of the endpoint doesn't have to be a predefined channel anymore

For a full demo of how to use this feature see : https://github.com/botpress/custom-channel

Closes DEV-2397

[linear]

DEV-2397 Custom channels

Allow using the endpoint api with custom channel names. These channel names should appear in webhooks. Requires a new table for custom channels

[fgrep]

Hello @samuelmasse. Can you provide the full demo for this feature? The link https://github.com/botpress/custom-channel does not exist. Thanks

[samuelmasse]

Hey @fgrep I changed the repo visibility to public, you can refer to it to implement your own custom channel. You can use bp.messaging that was added to the sdk in 12.27