Depreciated use of mb_convert_encoding()

[brianhogg]

Reproduction Steps

1. Enable debug/warning output
2. Embed a video in a lesson
3. View HTML of the wrapper (ie. with class llms-video-wrapper)

Expected Behavior

No warnings/errors shown

Actual Behavior

Depreciated:  mb_convert_encoding(): Handling HTML entities via mbstring is deprecated; use htmlspecialchars, htmlentities, or mb_encode_numericentity/mb_decode_numericentity instead in ...plugins/lifterlms/includes/class-llms-dom-document.php on line 136

This issue has be recreated:

• [ ] Locally
• [ ] On a staging site
• [ ] On a production website
• [ ] With only LifterLMS and a default theme

[brianhogg]

From this post, the alternative is to use utf8_decode https://stackoverflow.com/questions/11974008/alternative-to-mb-convert-encoding-with-html-entities-charset. However utf8_decode is also depreciated, and the alternative suggested is to use mb_convert_encoding()...

[brianhogg]

This should work:

htmlspecialchars_decode( htmlentities( $this->source, ENT_COMPAT, 'UTF-8'), ENT_COMPAT);

[brianhogg]

htmlspecialchars_decode( htmlentities( $this->source ) ) (or with flags in the comment above) doesn't work for all the cases in test_llms_get_dom_document(). Not sure what a reliable alternative is.

[brianhogg]

Created a custom one that does pass all the tests around the encoding, but some other PHPUnit tests are failing. Switched PR to draft.