implement Eq and Hash for some immut types

[yj-qin]

Related issue: #1177

1. Implement Hash for @immut/array
2. Implement Hash for @immut/list
3. Implement Hash and Eq for @immut/priority_queue
4. Implement Hash for @immut/sorted_map
5. Explicit implement Eq for some types.

[peter-jerry-ye-code-review]

Observed Problems and Suggestions

1. Redundant Implementation of op_equal in sorted_set/generic.mbt:

   • The op_equal function is implemented in sorted_set/generic.mbt, but it seems redundant given that Eq trait implementation can handle equality checks directly. This can be refactored to use the Eq trait directly.
   • Suggestion: Remove the redundant op_equal function and rely on the Eq trait implementation for equality checks.

2. Missing Eq Trait Implementation for T[A] in sorted_set/sorted_set.mbti:

   • The op_equal function is explicitly implemented in sorted_set/generic.mbt, but there is no Eq trait implementation for T[A] in sorted_set/sorted_set.mbti.
   • Suggestion: Add the Eq trait implementation for T[A] in sorted_set/sorted_set.mbti to ensure consistency and leverage trait-based equality checks.

3. Potential Performance Issue in op_equal Implementation:

   • The op_equal function in sorted_set/generic.mbt manually iterates through the elements to check for equality, which might be inefficient for large sets. Using the Eq trait directly can leverage optimized implementations provided by the language.
   • Suggestion: Refactor the op_equal function to use the Eq trait for better performance and code consistency.

By addressing these issues, the code will be more concise, maintainable, and potentially more efficient.

[coveralls]

Pull Request Test Coverage Report for Build 3871

Details

• 5 of 5 (100.0%) changed or added relevant lines in 4 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.06%) to 80.118%

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Totals
Change from base Build 3867:	0.06%
Covered Lines:	4356
Relevant Lines:	5437

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💛 - Coveralls

[bobzhang]

FTR, performance wise, this may be improved in the future

[bobzhang]

cc @lynzrand this is redundant, given Compare: Eq