cve-check: extract extending CVE_STATUS to library function

cve-check: extract extending CVE_STATUS to library function

The same code for extending CVE_STATUS by CVE_CHECK_IGNORE and
CVE_STATUS_GROUPS is used on multiple places.
Create a library function to have the code on single place and ready for
reuse by additional classes.

Conflicts:
  meta/classes/cve-check.bbclass
  meta/lib/oe/cve_check.py

Signed-off-by: Peter Marko <peter.marko@siemens.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 45e18f4270d084d81c21b1e5a4a601ce975d8a77)
Signed-off-by: Benjamin Robin (Schneider Electric) <benjamin.robin@bootlin.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>