feat: add Naive Pattern Search algorithm

This commit adds the Naive Pattern Search algorithm implementation in Java. 
The algorithm scans the text from left to right and checks each substring of 
length m (pattern length) to find matches.

- New class: NaivePatternSearch.java
- Provides `search(String text, String pattern)` method returning all match indices
- Includes a sample main() for demonstration

Time Complexity: O(n * m)
Space Complexity: O(1)

Author: Karthikn-VR

src/main/java/com/thealgorithms/strings/NaivePatternSearch.java

@@ -0,0 +1,33 @@
+package strings;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Naive Pattern Searching algorithm.
+ * Reference: https://en.wikipedia.org/wiki/String-searching_algorithm#Na%C3%AFve_string_search
+ */
+public class NaivePatternSearch {
+
+    /**
+     * Finds all occurrences of a pattern in a given text using
+     * the naive substring search algorithm.
+     *
+     * @param text    The text in which to search.
+     * @param pattern The pattern to search for.
+     * @return List of starting indices where the pattern is found.
+     */
+    public static List<Integer> search(String text, String pattern) {
+        List<Integer> result = new ArrayList<>();
+        int n = text.length();
+        int m = pattern.length();
+
+        for (int i = 0; i <= n - m; i++) {
+            String sub = text.substring(i, i + m);
+            if (sub.equals(pattern)) {
+                result.add(i);
+            }
+        }
+        return result;
+    }
+}