Fix test failing on windows. Also fix missing space in error message.

It's actually better if we don't show the specific path in the error
message.

Author: raph-amiard

lkql_jit/language/src/main/java/com/adacore/lkql_jit/langkit_translator/passes/TranslationPass.java

@@ -622,9 +622,8 @@ public LKQLNode visit(Liblkqllang.PatternDetailDelimiterIs patternDetailDelimite
                 .emitDiagnostic(
                         CheckerUtils.MessageKind.WARNING,
                         "'is' syntax is deprecated for patterns. Please consider migrating your"
-                                + " code via 'lkql refactor -r IS_TO_COLON"
-                                + patternDetailDelimiterIs.getUnit().getFileName()
-                                + "'.",
+                                + " code via 'lkql refactor -r IS_TO_COLON "
+                                + "path/to/your/rule_file.lkql'.",
                         null,
                         SourceSectionWrapper.create(
                                 patternDetailDelimiterIs.getSourceLocationRange(), source));

testsuite/tests/gnatcheck_errors/lkql_syntax_warning/test.out

@@ -1,4 +1,4 @@
-gnatcheck: foo.lkql:4:29: 'is' syntax is deprecated for patterns. Please consider migrating your code via 'lkql refactor -r IS_TO_COLON/rules/foo.lkql'.
+gnatcheck: foo.lkql:4:29: 'is' syntax is deprecated for patterns. Please consider migrating your code via 'lkql refactor -r IS_TO_COLON path/to/your/rule_file.lkql'.
 1. Summary
 
    fully compliant sources               : 1