Add callback resolver method

[AnuradhaSK]

Proposed changes in this pull request

• Add a protected method named resolveCallBackURLForAPIBasedAuthFlow to resolve the callback in the API_BASED authentication flow.

• Changing the callback URL to the client application's callback URL in initiateAuthenticationRequest method and getAccessTokenRequest could affect the OIDC authenticators used for internal purposes.

• resolveCallBackURLForAPIBasedAuthFlow method gives the capability to override the behavior in other authenticators if required.

Part of the first issue of https://github.com/wso2/product-is/issues/19668

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PR builder started Link: https://github.com/wso2/product-is/actions/runs/7939144695

[jenkins-is-staging]

PR builder completed Link: https://github.com/wso2/product-is/actions/runs/7939144695 Status: success