snort: validate sw_if_index in attach/detach api handlers

snort: validate sw_if_index in attach/detach api handlers

- fixes crash in vpp-debug-verify-master-ubuntu2204-x86_64 CI job
  in test_snort_06_detach_if testcase
- fix similar logic in attach handler
- verify snort direction in attach api message
- add tests verifying attribute validation in attach testcase

Type: fix
Fixes: 102575492c9199259aa5e468f21b46936d7a1ac4

Change-Id: I96fbeb0a7b84f2f238df15b20476ed4086251471
Signed-off-by: Dave Wallace <[email protected]>
(cherry picked from commit 2b85ab67f9d2163d83d4a68eb32de051c09c9a78)