Add IE support as an optional feature

[jaredlt]

Problem

IE does not support data-uri links https://caniuse.com/#feat=datauri

This means the links created via ical_url, apple_url and outlook_url will not download successfully in IE.

Solution

Add optional feature which you can enable that creates the *.ics file on the server and serves it as a normal download.

This will require users to configure a route in their application

[jaredlt]

Internet Explorer was officially retired on 15 June, 2022 and market share is less than 2%. Closing this.