Feature/kruskal mst

[prasanth-30011]

This PR adds an implementation of Kruskal’s Algorithm for computing the Minimum
Spanning Tree (MST) of a weighted undirected graph, addressing Issue #7067.

✔ What’s Included

• Added KruskalMST.java under com.thealgorithms.greedyalgorithms
• Added a clean and efficient implementation using:
  • Greedy approach
  • Disjoint Set Union (Union-Find) with path compression
  • Edge class with comparable interface for sorting
• Added unit tests KruskalMSTTest.java that verify:
  • Correct MST weight for a sample connected graph
  • Correct handling of disconnected graphs (returns -1)

✔ Why This is Useful

• Kruskal’s Algorithm is a core greedy technique frequently used in:
  • Competitive programming
  • Graph theory education
  • Interview preparation
• Adds missing MST support to the greedy algorithms library
• Completes the request made in Issue [FEATURE REQUEST] Add Kruskal’s algorithm #7067

🧪 Tests

All tests pass successfully using:

[codecov-commenter]

Codecov Report

❌ Patch coverage is 96.49123% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.52%. Comparing base (e6c576c) to head (bf8b2d3).

Files with missing lines	Patch %	Lines
...com/thealgorithms/greedyalgorithms/KruskalMST.java	95.45%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7088      +/-   ##
============================================
+ Coverage     78.46%   78.52%   +0.05%     
+ Complexity     6746     6744       -2     
============================================
  Files           758      759       +1     
  Lines         22339    22368      +29     
  Branches       4384     4389       +5     
============================================
+ Hits          17528    17564      +36     
+ Misses         4107     4099       -8     
- Partials        704      705       +1     

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