Prevent jinja2 from escaping HTML markup in collection metadata

[tw4l]

Description

This PR adds jinja2 safe filters to metadata values and an {% autoescape false %} block to the collection title in the search template to prevent HTML markup in collection metadata from being escaped.

Motivation and Context

Connected to #727

This fixes a regression in more recent versions of pywb which was reported by users.

Screenshots (if appropriate):

Before

(copied from linked issue)

After

Types of changes

• Replay fix (fixes a replay specific issue)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added or updated tests to cover my changes.
• All new and existing tests passed.

[ikreymer]

@tw4l looks good, yeah I think this started happening with autoescape being defaulted to true..
Since this isn't tied to 2.7.0, mind rebasing this off main, and then we can just merge it in separately

[tw4l]

@ikreymer no problem! this is now rebased and ready to merge

[tw4l]

I hadn't noticed there was a new commit on main upstream - should be good now :)

[ArtHoff]

Hi,
Thank you for addressing this issue, however there is still an issue with the HTML rewrite.
On the home page the first URL is clickable, but the one in the comment is displayed as HTML.

I expect to see:

But instead it shows:

Thanks for looking into this.