Add Ballerina language (#3818)

* Add Ballerina language

* Add missing file

* Update color

* Update with required changes

* Update sub-module

samples/Ballerina/xml.bal

@@ -0,0 +1,26 @@
+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);
+
+}