Implement a unit test for `getCharUnicodeCategory` in `src/core/unicode.js` (PR 14428 follow-up)
Implement a unit test for `getCharUnicodeCategory` in `src/core/unicode.js` (PR 14428 follow-up)

Given that the other functions in this file are already covered by unit
tests, we should also cover this newly added function.

nawawi/pdf.js,showpad/mozilla-pdf.js,nawawi/pdf.js,timvandermeij/pdf.js,mozilla/pdf.js,Snuffleupagus/pdf.js,mozilla/pdf.js,Shoobx/pdf.js,Snuffleupagus/pdf.js,macroplant/pdf.js,timvandermeij/pdf.js,Shoobx/pdf.js,nawawi/pdf.js,Shoobx/pdf.js,showpad/mozilla-pdf.js,mozilla/pdf.js,timvandermeij/pdf.js,Snuffleupagus/pdf.js,showpad/mozilla-pdf.js,macroplant/pdf.js,macroplant/pdf.js