Test for various non-breaking spaces

What does this MR do?

Clones some of the code already in scripts/lint-doc.sh to test for two types of non-breaking spaces.

The output returns the entire line - I wonder if there's a way (see https://superuser.com/questions/914856/display-all-output-but-highlight-search-matches for ideas) to highlight what space is the problem.

Sending over to @eread and @marcel.amirault to noodle on.

Related issues

• Related to #281082 (closed)
• Related to #26446 (closed)

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