[RFC]: add `string/base/slice-code-points`

[kgryte]

This task should implement a functional API for slicing a string based on Unicode code points.

The behavior should not match the built-in String.prototype.slice, as the function should properly handle surrogate pairs. All arguments should be required:

sliceCodePoints( str, start, end )

Related: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/string/base/for-each-code-point

Time estimate without AI: 4hrs
Time estimate with AI: 2-3hrs

[headlessNode]

PR: stdlib-js/stdlib#5414
Time till opening PR: 1hr 44 mins
AI Model: Claude 3.5 sonnet
Loom Recording: Link

[headlessNode]

Notes:

• Cursor performed exceptionally well on this task. The main function implementation was completed in about 40-45mins. Rest of the time spent was on writing appropriate tests, benchmarks and documentation.

• The reason for Cursor's performance on this task, in my opinion, was because:

  1. I used a detailed prompt explaining the functions' behavior.
  2. For codebase context various functions with similar logic were also available.
  3. The function signature was simple, due to which there were no issues with typescript declarations unlike other functions with complex signatures.

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Post PR Review Notes:

• A couple of refactors were made based on code review. Nothing major.

• Additional time spent: 4 mins.