Add support for ServiceTitan (client credentials grant)

[rguldener]

ServiceTitan has an API that can be used both by customers and external developers.
It only offers client credentials OAuth grants: https://developer.servicetitan.io/docs/oauth20/
Notably, API key is also not supported.

To install a developer's app, the customer has to setup a new OAuth app within their account. Then share the client id & client secret with the developer. See description here

As of time of opening this issue, Nango does not support client credentials grant, so support for this would need to be added first (plus support for passing in client id & secret with nango.auth)

[ansario]

Do we know when this will be prioritized? @bastienbeurier

[bastienbeurier]

Hi @ansario, we unfortunately don't have a timeline for this since it requires a platform change. I know ServiceTitan plans to implement the standard authorization code flow as well.