Add prometheus metrics for Central controllers (#1969)

* add header-only prometheus lib to ext

* rename folder

* Undo rename directory

* prometheus simpleapi included on mac & linux

* wip

* wire up some controller stats

* Get windows building with prometheus

* bsd build flags for prometheus

* Fix multiple network join from environment entrypoint.sh.release (#1961)

* _bond_m guards _bond, not _paths_m (#1965)

* Fix: warning: mutex '_aqm_m' is not held on every path through here [-Wthread-safety-analysis] (#1964)

* Serve prom metrics from /metrics endpoint

* Add prom metrics for Central controller specific things

* reorganize metric initialization

* testing out a labled gauge on Networks

* increment error counter on throw

* Consolidate metrics definitions

Put all metric definitions into node/Metrics.hpp.  Accessed as needed
from there.

* Revert "testing out a labled gauge on Networks"

This reverts commit 499ed6d95e11452019cdf48e32ed4cd878c2705b.

* still blows up but adding to the record for completeness right now

* Fix runtime issues with metrics

* Add metrics files to visual studio project

* Missed an "extern"

* add copyright headers to new files

* Add metrics for sent/received bytes (total)

* put /metrics endpoint behind auth

* sendto returns int on Win32

---------

Co-authored-by: Leonardo Amaral <leleobhz@users.noreply.github.com>
Co-authored-by: Brenton Bostick <bostick@gmail.com>

ext/prometheus-cpp-lite-1.0/3rdpatry/http-client-lite/examples/simple_request.cpp

@@ -0,0 +1,43 @@
+/*
+ *  example for httpclientlite.hxx
+ */
+
+#include <iostream>
+#include <map>
+#include <string>
+
+#include <jdl/httpclientlite.h>
+
+
+using namespace jdl;
+
+
+int main(int argc, char *argv[]) {
+  if (argc == 1) {
+    std::cout << "Use " << argv[0] << " http://example.org" << std::endl;
+    return EXIT_SUCCESS;
+  }
+
+  HTTPResponse response = HTTPClient::request(HTTPClient::POST, URI(argv[1]));
+
+  if (!response.success) {
+    std::cout << "Request failed!" << std::endl;
+    return EXIT_FAILURE;
+  }
+
+  std::cout << "Request success" << endl;
+
+  std::cout << "Server protocol: " << response.protocol << std::endl;
+  std::cout << "Response code: " << response.response << std::endl;
+  std::cout << "Response string: " << response.responseString << std::endl;
+
+  std::cout << "Headers:" << std::endl;
+
+  for (stringMap::iterator it = response.header.begin(); it != response.header.end(); ++it) {
+    std::cout << "\t" << it->first << "=" << it->second << std::endl;
+  }
+
+  std::cout << response.body << std::endl;
+
+  return EXIT_SUCCESS;
+}