refactor: rename files to follow Go convention

testdata/json_data_format_atomic.go

@@ -0,0 +1,13 @@
+package fixtures
+
+import (
+	"sync/atomic"
+)
+
+type Counter uint64
+
+func AtomicTests() {
+	x = atomic.AddUint64(&x, 1) // json:{"MATCH": "direct assignment to atomic value","Confidence": 1}
+	x := uint64(1)
+
+}