Proper Chinese translation for Select2 library strings

Problem/Motivation

The issue is what Drupal core calls "zh-hans", select2 library calls "zh-CN". So Select2's own messages remain English for Chinese user interface language.

Steps to reproduce

Configure a multilingual site, Select2 UI elements get translated into French, Spanish, etc, but not to Chinese.

Proposed resolution

Patch the underlying library to satisfy the missing language code.

A composer.json snippet inside patches

            "npm-asset/select2": {
              "Harmonize locale names with Drupal core": "patches/select2-zh-hans.patch"
            }

and a patch for the library solves this inconsistency. Symlinking zh-CN.js file is not enough, it contains a language code ID. That's why Drupal-level string and replace won't work either.

Remaining tasks

Figure out how to make it maintainable on the long run.

User interface changes

Not applicable.

API changes

Not applicable.

Data model changes

Not applicable.