Add test for check for compiling .ml of parameter .mli

I've disabled the check on the output, since currently we get the wrong error
message (and the one we get is confusing). This will be much easier to fix when
PR ocaml-flambda#1764 is fixed to avoid unhelpful checks on `.mli` files that are loaded
directly rather than as part of name resolution.

Author: lukemaurer

ocaml/testsuite/tests/templates/basic/bad_param_impl.ml

@@ -0,0 +1,18 @@
+(* TEST
+
+readonly_files = "bad_param_impl.mli bad_param_impl.reference"
+
+* setup-ocamlc.byte-build-env
+** ocamlc.byte
+flags = "-as-parameter"
+module = "bad_param_impl.mli"
+*** ocamlc.byte
+flags = ""
+module = "bad_param_impl.ml"
+ocamlc_byte_exit_status = "2"
+compiler_output = "bad_param_impl.output"
+**** skip
+reason = "error currently broken"
+***** check-ocamlc.byte-output
+compiler_reference = "bad_param_impl.reference"
+*)

ocaml/testsuite/tests/templates/basic/bad_param_impl.mli

@@ -0,0 +1 @@
+(* To be compiled with [-as-parameter] *)