chore: make Snapshot constructor public (#234)

Author: korniltsev-grafanista

agent/src/main/java/io/pyroscope/javaagent/Snapshot.java

@@ -13,7 +13,7 @@ public final class Snapshot {
     public final byte[] data;
     public final JfrLabels.LabelsSnapshot labels;
 
-    Snapshot(Format format, final EventType eventType, final Instant started, final Instant ended,final byte[] data, JfrLabels.LabelsSnapshot labels) {
+    public Snapshot(Format format, final EventType eventType, final Instant started, final Instant ended,final byte[] data, JfrLabels.LabelsSnapshot labels) {
         this.format = format;
         this.eventType = eventType;
         this.started = started;