reverse tool, testCases then updated index file

src/pages/string/reverse/service.ts

@@ -0,0 +1,31 @@
+import { reverseString } from 'utils/string';
+
+export function stringReverser(
+    input: string,
+    multiLine: boolean,
+    emptyItems: boolean,
+    trim: boolean
+) {
+    let array: string[] = [];
+    let result: string[] = [];
+
+    // split the input in multiLine mode
+    if (multiLine) {
+        array = input.split('\n');
+    }
+    else {
+        array.push(input);
+    }
+
+    // handle empty items
+    if (emptyItems){
+        array = array.filter(Boolean);
+    }
+    // Handle trim
+    if (trim) {
+        array = array.map(line => line.trim());
+    }
+
+    result = array.map(element => reverseString(element));
+    return result.join('\n');
+}