Add MinHeap and missing number solution

[ravithakur2k]

Introduced a MinHeap class with push, pop, top, and heapify methods in DesignMinHeap.py. Added a binary search-based solution for finding the missing number in a sequence in MissingNumber.py.

[super30admin]

• Strengths:
  • Correct implementation of binary search for finding the missing number.
  • Good understanding of time and space complexity.
  • Clear and readable code structure.
• Areas for Improvement:
  • The MinHeap class, while correctly implemented, is not relevant to the problem and should be omitted.
  • Fix the typo in the pop method of MinHeap (== should be =).
  • The MissingNumber.py solution could be simplified by removing redundant checks (e.g., elif mid + 1 != arr[mid] is redundant since it's the opposite of the first condition).