Check task with no-break space

What does this MR do and why?

Fix issue where tasks that contains non-breaking spaces were impossible to complete.

Fixes Tasks with non-breaking space can't be marked a... (#352695 - closed)

How to set up and validate locally

1. Create a new issue or merge request with the following description:

- [ ] NO-BREAK SPACE (U+00A0)
- [ ] FIGURE SPACE (U+2007)
- [ ] NARROW NO-BREAK SPACE (U+202F)
- [ ] THIN SPACE (U+2009)

2. Try to check all the checkboxes.

Changes in the description editor:

1. Enable the markdown_continue_lists feature flag in the rails console

   Feature.enable(:markdown_continue_lists)

2. Press Enter after each task items, it should add a new item

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.