feat: add truncate-middle-code-point string package

[steff456]

Part of #1062

Description

What is the purpose of this pull request?

This pull request:

• Adds @stdlib/string/base/truncate-middle-code-point

Related Issues

Does this pull request have any related issues?

This pull request:

• Part of Tracking issue: refactor string packages handling grapheme clusters in terms of "base" packages #1062

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

This PR depends on the packages,

• @stdlib/string/num-code-points available in feat: refactor truncate string package #1097
• @stdlib/string/next-code-point available in feat: add next-code-point-index string package #1117

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

---

@stdlib-js/reviewers

[kgryte]

We should refactor to require seq as a mandatory argument.

[kgryte]

This package needs to be renamed to plural.