Add falco engine info to --support output

In some cases, it might be useful to know what falco engine version a
given falco binary supports. We already have a --support option that
prints info about the system, config, rules files, etc.

Add a engine_info object, with an engine_version property containing the
falco engine version in falco_engine_version.h. In the output, it looks
like this:

...
  "engine_info": {
      "engine_version": 8
   },
...

Signed-off-by: Mark Stemm <mark.stemm@gmail.com>

userspace/falco/falco.cpp

@@ -41,6 +41,7 @@ limitations under the License.
 #include "event_drops.h"
 #include "configuration.h"
 #include "falco_engine.h"
+#include "falco_engine_version.h"
 #include "config_falco.h"
 #include "statsfilewriter.h"
 #ifndef MINIMAL_BUILD
@@ -939,6 +940,7 @@ int falco_init(int argc, char **argv)
 			support["system_info"]["version"] = sysinfo.version;
 			support["system_info"]["machine"] = sysinfo.machine;
 			support["cmdline"] = cmdline;
+			support["engine_info"]["engine_version"] = FALCO_ENGINE_VERSION;
 			support["config"] = read_file(conf_filename);
 			support["rules_files"] = nlohmann::json::array();
 			for(auto filename : config.m_rules_filenames)