website: Add better icon files

Generated from https://realfavicongenerator.net/

Signed-off-by: Jason Lowe-Power <jason@lowepower.com>
Change-Id: Ica9e7c1c68032b3212cf5e166d7587508a40cd37
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-website/+/31334
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: Bobby R. Bruce <bbruce@ucdavis.edu>
12 files changed