Append the scheme part of the HTTP client URL based on the client configurations

[ldclakmal]

Description:
This issue is created to track the improvement of appending the scheme part to HTTP client URL based on the client configurations.

Scenario - 1: Should append http:// to the URL

http:Client usersEP = check new("localhost:9090");

Scenario - 2: Should append https:// to the URL

http:Client usersEP = check new("localhost:9090",
    secureSocket = {
        cert: "./resources/public.crt"
    }
);

Scenario - 3: Should append https:// to the URL

http:Client usersEP = check new("localhost:9090",
    auth = {
        username: "alice",
        password: "123"
    }
);

Scenario - 4: Should append https:// to the URL

http:Client usersEP = check new("localhost:9090",
    auth = {
        username: "alice",
        password: "123"
    },
    secureSocket = {
        cert: "./resources/public.crt"
    }
);

Scenario - 5: Should be able to override the URL protocol as http:// for any of the above scenarios.

NOTE: But there will be a runtime warning if the protocol is overridden as http:// for scenario 2, 3 & 4.

http:Client usersEP = check new("http://localhost:9090",
    auth = {
        username: "alice",
        password: "123"
    },
    secureSocket = {
        cert: "./resources/public.crt"
    }
);

warning: [ballerina/http] HTTPS is recommended but using HTTP

In summary:

• If the scheme part is not provided & no security related configurations added, http:// scheme will be added.
• If the scheme part is not provided & one or more security related configurations are added, https:// scheme will be added.
• If the scheme part is added as http:// & one or more security related configurations are also added, there will be a warning.

Furthermore, this support should be extended to the client configurations of JWT and OAuth2 modules as well.

[ldclakmal]

Fixed with the above PRs.