Add check-only error tests

Author: rwy7

test/Dialect/FIRRTL/infer-domains-check-errors.mlir

@@ -0,0 +1,13 @@
+// RUN: circt-opt -pass-pipeline='builtin.module(firrtl.circuit(firrtl-infer-domains{mode=check}))' %s --verify-diagnostics --split-input-file
+
+// CHECK-LABEL: IncompleteDomainInformation
+firrtl.circuit "IncompleteDomainInformation" {
+  firrtl.domain @ClockDomain
+
+  firrtl.module private @Foo(
+    // expected-error @below {{missing "ClockDomain" association for port "x"}}
+    in  %x: !firrtl.uint<1>
+  ) {}
+
+  firrtl.module @IncompleteDomainInformation() {}
+}