refactor: rename files to follow Go convention

testdata/unused_param_custom_regex.go

@@ -0,0 +1,12 @@
+package fixtures
+
+// all will ok with xxxParam if Arguments = [{allowRegex="^xxx"}]
+
+func f0(xxxParam int) {}
+
+// still works with _
+
+func f1(_ int) {}
+
+func f2(yyyParam int) { // MATCH /parameter 'yyyParam' seems to be unused, consider removing or renaming it to match ^xxx/
+}