Move oidc .well-known from middleware to static routes

[dragonchaser]

Currently the oidc .well-knowns are intercepted using a middleware https://github.com/owncloud/ocis/blob/master/services/proxy/pkg/middleware/oidc_well-known.go this needs to be moved to the proxy into the static router handler that is introduced in #6007.

[stale]

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