feat: Added Dispute entity

[ankitdas13]

• fetch all dispute
• fetch a dispute
• Accept a dispute
• Contest a dispute

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (753c07b) 89.95% compared to head (4184fda) 90.09%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #391 +/- ## ========================================== + Coverage 89.95% 90.09% +0.14% ========================================== Files 27 28 +1 Lines 906 919 +13 ========================================== + Hits 815 828 +13 Misses 91 91 ```

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