Move html templates into separate files

[llewelld]

Summary

As a developer of the site, I would like the <template/> items to be in separate files so that I can easily dilneate them from other portions of the jinja2 page templates.

Apart from helping to improve the overall structure, making this change will also make it easier to update the moderation replies and alert messages should they need to be later.

Deadline

What needs to be done?

• [ ] Check the dialogue text <template/> items in the moderate_experience.html file and move them to a separate file.
• [ ] Check the moderation reply <template/> items in the moderate_experience.html file move them to a separate file.

Who can help?

• Anyone comfortable with modifying the template files.

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Updates

[llewelld]

See @gedankenstuecke's comment for the context: https://github.com/alan-turing-institute/AutSPACEs/pull/547#discussion_r1267067249.