feat: create a sanitized html fragment component for reuse across MFEs

[rediris]

• specifically, this PR replaces the LmsHtmlFragment IFRAME with a SanitizedHtmlFragment in the CourseHandouts component.

[openedx-webhooks]

Thanks for the pull request, @rediris!

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[rediris]

@bradenmacdonald thoughts?

[bradenmacdonald]

@rediris Can you please provide more context for this change, as well as screenshots, etc?

I'm not sure I fully understand this, but if my assumptions are correct, this is a backwards-incompatible change. LmsHtmlFragment renders the given HTML (handouts) with the LMS legacy CSS stylesheet and no HTML sanitization. This PR renders the handouts with HTML sanitization and with the frontend-app-learning CSS, which is going to affect the content very differently.

So, I like your approach much better, but I need more information to decide if it makes sense, if it needs product review, and/or if it's going to break anyone's existing handouts content.

[rediris]

@rediris Can you please provide more context for this change, as well as screenshots, etc?

I'm not sure I fully understand this, but if my assumptions are correct, this is a backwards-incompatible change. LmsHtmlFragment renders the given HTML (handouts) with the LMS legacy CSS stylesheet and no HTML sanitization. This PR renders the handouts with HTML sanitization and with the frontend-app-learning CSS, which is going to affect the content very differently.

So, I like your approach much better, but I need more information to decide if it makes sense, if it needs product review, and/or if it's going to break anyone's existing handouts content.

Hi @bradenmacdonald, good thoughts. Perhaps one alternative would be to enable this feature with a waffle flag.

My reasoning behind this is somewhat personal - I have a deep disdain for IFRAMEs and the oft unwieldy code written to support their use. While the course units rely on IFRAMEs to deliver content, the handouts are (generally) static html and I see them as low-hanging fruit for this type of change.

Give me a couple of days to assemble some screenshots and double check the UX/UI for this change.

[bradenmacdonald]

Oh, I absolutely think your change is great, and removing this iframe would be great. I'm just worried it will be a breaking change and specifically a breaking change that affects content, and that's not something we can do without a lot of planning, consideration, and getting buy-in from whoever would be affected (if any).