Retire IE11 Support

[davidjoy]

While it may sound like maintenance, this is about how IE 11 holds us back from a number of newer technologies in the frontend, newer syntax, HTTP/2, i18n libraries, etc.

Related Jira tickets:

1. https://openedx.atlassian.net/browse/ENT-4830
2. https://openedx.atlassian.net/browse/WS-2132

• [x] Parse Segment page view events in Enterprise MFEs to understand IE usage across customers in the past year.
• [x] Identify the correct UI component to show to IE 11 users with messaging to inform them about upgrading to a new browser (e.g., Chrome). We will use the PageBanner component from Paragon, specifically the "warning" variant.
• [x] Sync with #website squad on any messaging needs there, and timeline for when to show the alert / PageBanner.
• [x] Select a way to conditionally render a component only IE users only (e.g., library). prospectus (edx.org) is using Google Tag Manager.
• [x] Implement in edx.org (prospectus)
• [ ] ~Implement in Enteprise MFEs.~ (decision: no messaging needed)
• [x] Inform the Support team of this decision.
• [x] Ensure IE is removed from supported browsers in Support Portal
• [ ] Identify and remove mention of IE in technical documentation.
• [x] Announce at the next FedX meeting and FWG meetings.
• [ ] Create Discourse post to let community know of this decision.
• [ ] Get this into Open edX release notes for Nutmeg
• [ ] Remove "ie 11" from browserslists throughout the platform (primarily MFEs) https://docs.google.com/spreadsheets/d/1fduFbAxIbckiwHKNCtc41ImAL_CFIl9hZcC4AjDkuvI/edit?usp=sharing
• [ ] Notify the Build-Test-Release working group.

[adamstankiewicz]

The decision has been made 😉 We have officially dropped support for Internet Explorer 11 as of today. Only 0.15% of users in the past 3 months on the B2C side of things (edx.org) used IE 11. In the Enterprise products, only 0.8% of users in the past 3 months used IE 11 (notably on the Enterprise Admin Portal).

The edx.org website implemented a banner with messaging about no longer supporting IE 11 for users viewing the site from that browser:

I updated the top-level issue description's task list to account for post-decision follow-ups around removing mentions of IE support from our support portal and documentation, to announce this decision at appropriate venues (e.g., FWG meeting), and to create a Discourse post to inform the community of this decision.

This decision is exciting because is unblocks several tech initiatives, including using CSS variables, simplifying frontend build processes, Bootstrap 5 upgrade, removing now-irrelevant polyfills, etc.

We do not plan to make any changes related to these initiatives prior to the Maple release of Open edX (the cut is tentatively ~ October 16).

[arbrandes]

We're pretty much done, here. :)