Various sudo (a.k.a. root-protected) paths are implemented in
non-standard ways, and as a result:

* are not declared as x-vault-sudo in the OpenAPI spec

* and as a result of that, are not included in the hardcoded patterns
  powering the Vault CLI `-output-policy` flag

* and in some cases are missing from the table of all sudo paths in the
  docs too

Fix these problems by:

* Adding `seal` and `step-down` to the list of root paths for the system
  backend. They don't need to be there for enforcement, as those two
  special endpoints bypass the standard request handling code, but they
  do need to be there for the OpenAPI generator to be able to know they
  require sudo.

  The way in which those two endpoints do things differently can be
  observed in the code search results for `RootPrivsRequired`:
  https://github.com/search?q=repo%3Ahashicorp%2Fvault%20RootPrivsRequired&type=code

* Fix the implementation of `auth/token/revoke-orphan` to implement
  endpoint sudo requirements in the standard way. Currently, it has an
  **incorrect** path declared in the special paths metadata, and then
  compensates with custom code throwing an error within the request
  handler function itself.

…onstant

Co-authored-by: Anton Averchenkov <[email protected]>