Unneeded IE11 compatibility in download button causes confusion

[rtibbles]

Observed behavior

User noted that when downloading a resource file (from a BCK server resource page under Learn, to your local device) it can take a long time to initiate (minutes). I observed that it seems to fully download the file in the background before giving any indication that something is happening and popping up the box to choose where to save it to.

Expected behavior

Download should start immediately.

This can be best achieved by just using an <a> tag with the download attribute set to the frontend generated filename.

This could either be handled within the download method, or perhaps, even more simply just added in the markup.

User-facing consequences

Confusion, not sure if file is downloading or not, perception of downloading being slow.

Steps to reproduce

Download a large file from the Kolibri UI, from a remote server (e.g. BCK) or an artificially slowed-down local connection.

Context

• Kolibri version: 0.17.0

[rtibbles]

Fixed in #12675