Decode mdash character before rendering the title

[dinhtungdu]

Description of the Change

Decode mdash character before rendering the title. This fixes #43.

Alternate Designs

Benefits

Make the UX less confusing when ordering child pages.

Possible Drawbacks

Verification Process

Checklist:

1. Go to admin > Pages.
2. Change order for child pages.
3. See: After changing order, the title display — character correctly (same as before).

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests passed.

Applicable Issues

Changelog Entry

[helen]

This seems fine for now, though we will probably trigger a warning about innerHTML again. The @wordpress/html-entities package does basically this though, just with an extra conditional usage of document.implementation.createHTMLDocument that falls back to this method. So, we should probably switch to that package later, I just don't want to introduce anything more complex in a hotfix release. I'm going to merge this, but let's open an issue for 2.4 to see about using the package and if that will avoid us getting dinged by automated scanners, and also an issue to automate the build process and stop committing the built JS file :)