fix #2865 Refactor Ingester to enhance testability by adding getInges…

…tFactory method.

src/main/java/org/codelibs/fess/ingest/Ingester.java

@@ -36,7 +36,11 @@ public void setPriority(final int priority) {
     }
 
     public void register() {
-        ComponentUtil.getIngestFactory().add(this);
+        getIngestFactory().add(this);
+    }
+
+    protected IngestFactory getIngestFactory() {
+        return ComponentUtil.getIngestFactory();
     }
 
     // web/file