Map `ACIError: Insufficient access` to 404

[tiran]

When principal has no permission to set or get an entry, FreeIPA fails with an exception like

ACIError: Insufficient access: Insufficient 'add' privilege to add the entry 'cn=keys__secrets__test10,cn=custodia/client1.ipa.example@IPA.EXAMPLE,cn=services,cn=vaults,cn=kra,dc=ipa,dc=example'

custodia.ipa should map the exception to HTTP 404 error.

[tiran]

Depends on custodia 0.4 with latchset/custodia#177