Make Solid OS compatible with ESS

[michielbdejong]

In order to make Solid OS compatible with https://pod-compat.inrupt.com/ we need (afaik) 5 things:

• [ ] Use webid-oidc-dpop instead of webid-oidc-legacy
• [ ] Use Etags instead of sparql-update semaphore
• [ ] Wait for https://github.com/solid/specification/issues/246#issuecomment-795084362 to be resolved
• [x] Deal with non-public acl links
• [ ] Wait for https://github.com/solid/specification/issues/193#issuecomment-795088636 to be resolved

[michielbdejong]

Thanks to https://github.com/solid/specification/pull/248#issuecomment-802656538 Solid OS can just assume that a rel="acl" response header exists on the response of any successful GET or HEAD request. 1 down, 4 to go! :)

[michielbdejong]

Also, Inrupt are dropping WAC support now.