Create credentials via API

[taylordowns2000]

Background

As an administrator of an external system, I'd like to provide my users with an interface that allows them to enable a specific OpenFn-hosted workflow by simply selecting that workflow and providing the necessary credential data.

Follow the steps, 1 to 4, in the diagram below to see the flow from the external system to OpenFn.

The scope of this issue

This issue is about creating a REST API for credentials, which will allow a properly authenticated request from an external system (or a CURL from a command line) to securely create a credential in OpenFn and add it to one or more projects. (NOTE: see current MSF credential creation via command line implementation.)

Keychain credentials are already handled.

Acceptance Criteria

• I should be able to make an HTTP request using curl with clear parameters in a secure way that adds a new credential to OpenFn and grants access to a specific project