Add Java solution for First Non-Repeated Character in a String

[Piyush-Kumar62]

Problem

Find the first non-repeated character in a string.

Approach

• Used a LinkedHashMap to store the frequency of each character while maintaining insertion order.
• Iterated over the map to find the first character with a count of 1.
• Added detailed comments and explanation in the code.

Time & Space Complexity

• Time Complexity: O(n)
• Space Complexity: O(n)

Example Inputs & Outputs

• Input: "swiss" → Output: "First non-repeated character: w"
• Input: "hello" → Output: "First non-repeated character: h"

This PR adds a clean, well-explained Java solution ready for DSA repository.