Improve escaping on the web interface

[DL6ER]

What does this implement/fix?

Fixes pi-hole/FTL#1760, see pi-hole/FTL#1760 (comment) for additional context.

Before:

After:

Related issue or feature (if applicable): N/A

Pull request in docs with documentation (if applicable): N/A

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[yubiuser]

Interesting, that setting the content type works for us, but not for some users reported here: https://bugs.jquery.com/ticket/12326/

[DL6ER]

The small glitch I observed isn't a web issue. It will be fixed by pi-hole/FTL#1763 so I'd say this PR is indeed ready for review.

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Interesting, that the setting the content type works for us, but not for some users reported here: https://bugs.jquery.com/ticket/12326/

These last comments you are referring to are over 9 years old, though. I guess the issue was fixed meanwhile but just nobody remembered this issue ticket (it is "closed as invalid").

[github-actions]

This pull request has conflicts, please resolve those before we can evaluate the pull request.

[github-actions]

Conflicts have been resolved.