options: Cleanup and simplify options_postprocess_verify_ce

options: Cleanup and simplify options_postprocess_verify_ce

- Reuse the MUST_BE_UNDEF macro in more places
- Add a second parameter so it actually reports the
  correct option name
- Add MUST_BE_FALSE for similar cases
- Reorder the checks for cert/key options to make
  more sense. Some of the checks could have never
  fired due to wrong placement of the management
  checks
- Some other small cleanups like missing spaces
  in multiline string literal

Change-Id: I4f766fa22865eaf4466c31cf55e3d73b00008c38
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20250318155320.32573-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg31155.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>