Remove support for Internet Explorer

[jonkoops]

Internet Explorer has been unmaintained for years, hence the InternetExplorerDriver is just dead weight as this point and should be removed. See earlier discussion under #402

[WolfgangHG]

Just found this issue and want to add my 2 cents:
HtmlUnitDriver 4.19.1 (which is contained in the 3.0.0.Alpha8 drone release) already removed IE support:
SeleniumHQ/htmlunit-driver@acd31a9