Common Cartridge special path token changed from $IMS-CC-FILEBASE$ to $1EdTech-CC-FILEBASE$

[ywarnier]

When IMS Global changed name to 1EdTech, they also changed the name of the "special token" used to substitute root paths for filepaths in the Common Cartridge standard from $IMS-CC-FILEBASE$ to $1EdTech-CC-FILEBASE$. See https://www.imsglobal.org/cc/ccv1p3/imscc_Implementation-v1p3.html#toc-79 (Section 3.4.3.3).

This is confusing, of course, but I couldn't help but notice Canvas still (and only) uses the old syntax here: https://github.com/instructure/canvas-lms/blob/4962f2693ab8c292dc5c986af5bd61611e68a461/lib/cc/importer/standard/converter.rb#L163

This might cause issues when importing from other systems using the new token.

I think it would be good to add support for the new syntax too, for example by changing FILEBASE_REGEX = /\$IMS[-_]CC[-_]FILEBASE\$/ to FILEBASE_REGEX = /\$(?:IMS|1EdTech)[-_]CC[-_]FILEBASE\$/

I'm happy to submit a PR for that, but not being used to contribute to Canvas, I would like to get approval first.