Update 0200-number-of-islands.ts

[M0Leo]

• File(s) Modified: 0200-number-of-islands.ts
• Language(s) Used: TypeScript
• Submission URL: https://leetcode.com/problems/number-of-islands/

[Ykhan799]

@M0Leo Instead of deleting the BFS solution, you should add your DFS solution below.