feat(jsinput): Allow JSInput problems to create downloads

Description

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    1. Description

A small fix for a small issue.

As of fairly recently, browser security settings prevent sandboxed iframes from creating downloads in certain browsers - downloads are still acceptable in Safari, but not Chrome and Firefox. We have a small number of [jsinput problems](https://edx.readthedocs.io/projects/edx-partner-course-staff/en/latest/exercises_tools/custom_javascript.html) that are affected by this, including in a course that just went live ([Early Childhood Development](https://www.edx.org/course/early-childhood-development-global-strategies-for-implementation) on edx.org). This slipped through testing because, well, "fairly recently."

We're getting around the limitation right now by having everyone right-click, open in new tab, and then download the resulting PDF, but it would be nice to not deal with this limitation in the future.

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    1. Deadline

None.

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    1. Other information

Given that the pages iframed into JSInput problems are always controlled by partners, typically hosted in Files & Uploads, and have access only to the current user's data, the additional security risk from adding "allow-downloads" to the sandbox list feels minimal.

Sandbox attributes are not passed from the `<jsinput>` tag to the iframe, so the change can't be made on a problem-by-problem basis.

Done

Assignee

sburch

Reporter

Open Source Pull Request Bot

Labels

Contributor Name

Colin Fredericks

Repo

edx/edx-platform

Customer

Epic Link

None

OSCM Assignee

None

Platform Map Area (Levels 1 &amp; 2)

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Platform Map Area (Levels 3 &amp; 4)

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Blended Hour Utilization Percentage

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edX Theme

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edX Squad

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Github Lines Added

4

Github Lines Deleted

3

Priority

Unset