Add COVID explorer redirects (master-merge)
Add COVID explorer redirects (master-merge)

OurWorldInData/owid-grapher,OurWorldInData/owid-grapher,OurWorldInData/owid-grapher,OurWorldInData/owid-grapher,owid/owid-grapher,owid/owid-grapher,OurWorldInData/owid-grapher,owid/owid-grapher,owid/owid-grapher,owid/owid-grapher