feat(data-structures): add BinarySearchTree methods ceiling, floor, higher, lower

[WWRS]

closes #3069

May break custom binary trees that reimplement BinarySearchTree.#findNode(). I think it's unlikely that anyone is doing that given that #findNode() should work on all child data structures of binary search trees. As pointed out, this is not a problem.

The new methods have the same time complexity as find().

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.30%. Comparing base (61f9fd3) to head (abbbf61).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6544   +/-   ##
=======================================
  Coverage   95.29%   95.30%           
=======================================
  Files         576      576           
  Lines       43315    43354   +39     
  Branches     6477     6489   +12     
=======================================
+ Hits        41279    41318   +39     
  Misses       1995     1995           
  Partials       41       41           

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[lionel-rowe]

May break custom binary trees that reimplement BinarySearchTree.#findNode()

It's not possible to reimplement #private methods in derived classes. Implementing a method with the same name in the derived class creates a new method that's only accessible within the derived class, rather than overriding the method in the parent.

class A {
    #private() {
        return 'A'
    }

    foo() {
        console.log(this.#private())
    }
}

class B extends A {
    #private() {
        return 'B'
    }

    bar() {
        console.log(this.#private())
    }
}

new A().foo() // logs 'A'
new B().foo() // still logs 'A'
new B().bar() // logs 'B'

[WWRS]

Ah, I see where I got confused. There's a change to an export in _binary_search_tree_internals and that gets used by RedBlackTree. I thought this meant RedBlackTree used some sort of extension of internals, but that's just exported to allow RedBlackTree access to those private methods. So the type change cannot cause any problems.