Revert backwards incompatible reva config changes

The commit of unifying the Reva Client config introduced some backwards
incompatible changes to the config structures and yaml config tags. For
the "thumbnails", "webdav" and "notifications" service. This reverts the
changes on the service and introduces TLS options in a backwards
compatible manner.
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Gitea Version: 1.28.0+dev-477-g8b6ad49a5f