Extract IncidentHeaderProto to a separated file for statsd to consume

Create a HeaderSection to deal with header protos which is more testable

Bug: 65422268
Test: unit tested
Change-Id: Icdcbeded8bc963940a8f9e503cb65a9a247ca5b2
diff --git a/cmds/incidentd/src/Section.h b/cmds/incidentd/src/Section.h
index 9cfd696..0a1e03e 100644
--- a/cmds/incidentd/src/Section.h
+++ b/cmds/incidentd/src/Section.h
@@ -45,6 +45,18 @@
 };
 
 /**
+ * Section that generates incident headers.
+ */
+class HeaderSection : public Section
+{
+public:
+    HeaderSection();
+    virtual ~HeaderSection();
+
+    virtual status_t Execute(ReportRequestSet* requests) const;
+};
+
+/**
  * Section that reads in a file.
  */
 class FileSection : public Section