Introduce a new Genetic Oauth2 key Manager

[jan1tha]

Problem

Currently, users are required to write a custom key manager each time a new key manager is required.

Proposed Solution

Implement a custom Key Manager connector for WSO2 APIM that supports JWT tokens using an Out-of-Band provisioning model.

Manual Provisioning: This is simply "Client Registration" performed out-of-band, as allowed by the spec.
JWT Validation: We are following RFC 7519. The Gateway validates the iss (issuer) and aud (audience) claims to ensure the token belongs to the mapped application.

Alternatives

No response

Version

apim-4.6.0

[dakshina99]

Doc update PR: wso2/docs-apim#10708