Umami support for Internet Explorer 11

Problem:

Umami theme has lots of display issues in Internet Explorer.

1. main menu links are not displayed - major usability bug
2. logo image is stretched vertically
3. Text in banner is at top of image, rather than midway down
4. Promoted Articles heights are equal but not correct
5. Frontpage view flexbox is not working (probably just need to add in a prefix ms-flex
6. Articles listing page - flexbox is not working
7. Article node - is sidebar working
8. Recipe node - same issue with sidebar
9. Recipe node - icons and text are squashed on top of each other
10. Recipe node - ingredients and instructions flexbox is not working
11. Taxonomy term page - flexbox not working
12. Search block - icon missing

Internet Explorer 11 is one of the supported browsers for D8.