Add Ballerina language (#3818)

* Add Ballerina language

* Add missing file

* Update color

* Update with required changes

* Update sub-module

samples/Ballerina/hello-world-service.bal

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+import ballerina.lang.messages;
+import ballerina.net.http;
+import ballerina.doc;
+
+@doc:Description {value:"By default Ballerina assumes that the service is to be exposed via HTTP/1.1 using the system default port and that all requests coming to the HTTP server will be delivered to this service."}
+service<http> helloWorld {
+    @doc:Description {value:"All resources are invoked with an argument of type message, the built-in reference type representing a network invocation."}
+    resource sayHello (message m) {
+        // Creates an empty message.
+        message response = {};
+        // A util method that can be used to set string payload.
+        messages:setStringPayload(response, "Hello, World!");
+        // Reply keyword sends the response back to the client.
+        reply response;
+    }
+}

samples/Ballerina/hello-world.bal

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+import ballerina.lang.system;
+
+function main (string[] args) {
+    system:println("Hello, World!");
+}
+

samples/Ballerina/json.bal

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+import ballerina.lang.system;
+
+function main (string[] args) {
+    // JSON string value.
+    json j1 = "Apple";
+    system:println(j1);
+
+    // JSON number value.
+    json j2 = 5.36;
+    system:println(j2);
+
+    // JSON true value.
+    json j3 = true;
+    system:println(j3);
+
+    // JSON false value.
+    json j4 = false;
+    system:println(j4);
+
+    // JSON null value.
+    json j5 = null;
+
+    //JSON Objects.
+    json j6 = {name:"apple", color:"red", price:j2};
+    system:println(j6);
+
+    //JSON Arrays. They are arrays of any JSON value.
+    json j7 = [1, false, null, "foo",
+               {first:"John", last:"Pala"}];
+    system:println(j7);
+}

samples/Ballerina/var.bal

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+import ballerina.lang.system;
+
+function divideBy10 (int d) (int, int) {
+    return d / 10, d % 10;
+}
+
+function main (string[] args) {
+    //Here the variable type is inferred type from the initial value. This is same as "int k = 5";
+    var k = 5;
+    system:println(10 + k);
+
+    //Here the type of the 'strVar' is 'string'.
+    var strVar = "Hello!";
+    system:println(strVar);
+
+    //Multiple assignment with 'var' allows you to define the variable then and there.
+    //Variable type is inferred from the right-hand side.
+    var q, r = divideBy10(6);
+    system:println("06/10: " + "quotient=" + q + " " +
+                   "remainder=" + r);
+
+    //To ignore a particular return value in a multiple assignment statement, use '_'.
+    var q1, _ = divideBy10(57);
+    system:println("57/10: " + "quotient=" + q1);
+
+    var _, r1 = divideBy10(9);
+    system:println("09/10: " + "remainder=" + r1);
+}

samples/Ballerina/xml.bal

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+import ballerina.lang.system;
+
+function main (string[] args) {
+
+	// XML element. Can only have one root element.
+    xml x1 = xml `<book>The Lost World</book>`;
+    system:println(x1);
+
+    // XML text
+    xml x2 = xml `Hello, world!`;
+    system:println(x2);
+
+    // XML comment
+    xml x3 = xml `<!--I am a comment-->`;
+    system:println(x3);
+
+    // XML processing instruction
+    xml x4 = xml `<?target data?>`;
+    system:println(x4);
+
+    // Multiple XML items can be combined to form a sequence of XML. The resulting sequence is again an XML on its own.
+    xml x5 = x1 + x2 + x3 + x4;
+    system:println("\nResulting XML sequence:");
+    system:println(x5);
+
+}