[BE] 10-10CG - Improvements: Update Form1010cg::Service to use new OAuth 2.0 Authorization Flow from MuleSoftClient in Dev

[coope93]

As a first step for implementing OAuth 2.0 Authentication for the 10-10CG form, we need to update the existing MuleSoftClient to use the new authentication flow.

• Should be behind flipper toggle
• Ensure we update all VCR cassettes as the api payload will be different with this change.
• Update any documentation around 10-10 CG and MuleSoft
• More than likely this will follow a client credential grant flow (confirmed this is the case) as it is service to service authentication.
• Helpful info for OAuth 2.0 Client Credential flow with Okta is here
• SI (DEV/QA) or DTC-I team (Stage/Prod) will create the application through AnyPoint Exchange for the API which is requested access by the consumer (va.gov)
• DTC-I team will provide us the auth server URL, Client Id, and Client Secret in an encrypted email. (These will need added to AWS Parameter Store with a platform support ticket)

Acceptance Criteria

• Development is complete and manually tested successfully, coordinating with Mulesoft for Dev credentials. Additional testing in Staging and potentially code changes due to testing are captured in a separate ticket.

[coope93]

Currently blocked on this while I wait for the MuleSoft team to get me staging credentials.

[coope93]

Confirmed today that test submissions from dev were showing up in CARMASIT dev environment. 🥳