@Kha Could you please double check these modifications.
I added a no-op for `checkRbpLt`. It is used at the `Sort` and `Type`
parsers.
As I described in previous commits, the `checkRBPGreater` comment and
implementation were misleading. It was actually succeeding when the
rbp was less than or equal to the given parameter. So, it was renamed
to `checkRbpLe`. So, is the depArrow parenthesizer ok? I did not check.
I updated the PPRoundtrip.lean.expected.out to make sure the tests
succeed, but we should revise it if there is a problem with the
modifications at Parenthesizer.lean
