[Import/Export] Improve link handling during course copy

[Andrew42]

Problem statement:

In courses that contain links to external webpages, Canvas completes the course copy except for the pages that contain these links. Sample links in footer div:

<div class="cell">
<ul>
<li><a class="instructure_file_link inline_disabled" href="http://#" target="_blank" rel="noopener"> <span>About Us</span> </a></li>
<li><a class="instructure_file_link inline_disabled" href="http://#" target="_blank" rel="noopener"> <span>Contact us</span> </a></li>
</ul>
</div>

Error message generated for both pages with this footer:

"Import Error: Wiki Page - "2.4 Homepage | Term 1"
Import Error: Wiki Page - "2.4 Homepage | Term 1"
An error occurred while translating content links"

Proposed solution:

Course copying should more robustly handle broken links during course copy. Canvas should copy all pages in the source course then offer to indicate these broken links via the Course Link Validation tool rather than failing to copy these pages at all. Because the affected pages aren't copied, staff are obliged to copy a suitable page from another course and adapt this to suit the copied course. If this page copy also doesn't work, staff are obliged to build the page from scratch.

User role(s):

admin,instructor,ta,designer