null-safe dereferencing doesn't affect with "in", "not in" and "contains"

Issue Description:

In exec-model, null-safe dereferencing "!." doesn't affect with "in" and "not in"

for example,

when
  $p : Person( address!.city in ("Milan", "Tokyo") )

doesn't generate null-check, so fails at runtime with NPE.

Acceptance Criteria:

Do null-check with "in" and "not in"