feat/df-820: Reads payment api key from secrets

[jbarnsley10]

Proposed change

Reads payment API keys from secrets served by forms-manager

Jira ticket: DF-820

Type of change

• Bug fix
• New feature
• Breaking change
• Misc. (documentation, build updates, etc)

Checklist

• You have executed this code locally and it performs as expected.
• You have added tests to verify your code works.
• You have added code comments and JSDoc, where appropriate.
• There is no commented-out code.
• You have added developer docs in README.md and docs/* (where appropriate, e.g. new features).
• The tests are passing (npm run test).
• The linting checks are passing (npm run lint).
• The code has been formatted (npm run format).

[davidjamesstone]

Although not part of this PR, it would be nice to move PaymentDispatcherArgs into types.ts and have it inherit from the base ExternalArgs. That way args.controller and args.controller.model are PageController and FormModel rather than custom objects.

https://github.com/DEFRA/forms-engine-plugin/pull/314/changes#diff-31b13e4392949f2e246107b05f25eab0f997373f2cc175ef3eaaccc1c5303269L346

Thanks Jez

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
97.4% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud