[Fixes #11862] Sanitize HTML data

[t-book]

Add a new template tag for legacy pages to sanitize html with nh3

Checklist

Reviewing is a process done by project maintainers, mostly on a volunteer basis. We try to keep the overhead as small as possible and appreciate if you help us to do so by completing the following items. Feel free to ask in a comment if you have troubles with any of them.

For all pull requests:

• Confirm you have read the contribution guidelines
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• Make sure the first PR targets the master branch, eventual backports will be managed later. This can be ignored if the PR is fixing an issue that only happens in a specific branch, but not in newer ones.

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• There is a ticket in https://github.com/GeoNode/geonode/issues describing the issue/improvement/feature (a notable exemption is, changes not visible to end-users)
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• Commit message must be in the form "[Fixes #<issue_number>] Title of the Issue"
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Submitting the PR does not require you to check all items, but by the time it gets merged, they should be either satisfied or inapplicable.

[t-book]

Test is failing with
45.08 AttributeError: module 'modeltranslation' has no attribute 'version'
I'll check

[giohappy]

@t-book probably you need to merge master

[t-book]

thanks @giohappy I've rebased

[giohappy]

@t-book I see there are conflicts to be resolved

[t-book]

@giohappy The PR became outdated with this PR some hours ago f07dd0c
I've solved the conflict.

[github-actions]

The backport to 4.2.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-4.2.x 4.2.x
# Navigate to the new working tree
cd .worktrees/backport-4.2.x
# Create a new branch
git switch --create backport-11859-to-4.2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 9d6a2469da510313006b6a95df8c01573607a49e
# Push it to GitHub
git push --set-upstream origin backport-11859-to-4.2.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-4.2.x

Then, create a pull request where the base branch is 4.2.x and the compare/head branch is backport-11859-to-4.2.x.

[giohappy]

@t-book can you take a look at the backport?