Support to overwrite the auth.scopes config of service annotation by resource annotation

[ldclakmal]

Description
Currently, the auth config of http:ServiceConfig annotation can be completely overwritten by the auth config of http:ReourceConfig annotation. But, there can be use cases where only the auth.scopes config should be overwritten per resource.

Example:

http:JwtValidatorConfig config = {
    issuer: "wso2",
    audience: "ballerina",
    signatureConfig: {
        certFile: "./resources/public.crt"
    }
};

listener http:Listener securedEP = new(9090,
    secureSocket = {
        key: {
            certFile: "./resources/public.crt",
            keyFile: "./resources/private.key"
        }
    }
);

@http:ServiceConfig {
    auth: [
        {
            jwtValidatorConfig: {
                issuer: "wso2",
                audience: "ballerina",
                signatureConfig: {
                    certFile: "./resources/public.crt"
                }
            }
        }
    ]
}
service /ordermgt on securedEP {

    @http:ResourceConfig {
        auth: {
            scopes: ["add_order"]
        }
    }
    resource function post 'order(@http:Payload Order 'order) returns http:Created {

    }

    @http:ResourceConfig {
        auth: {
            scopes: ["add_order"]
        }
    }
    resource function put 'order/[string orderId](@http:Payload UpdateOrder updateOrder) returns http:Ok|http:BadRequest {
        
    }
}