send PLDM event msg when state sensor changes

Add the D-Bus to event handler interface to listen all of the state
sensor PDRs and pldm should be able to send up a PLDM event msg when a
D-Bus property changes. the PlatformEventMessage command format is
defined in Table 15 in DSP0248 v1.2.0.

Tested: test with JSON
https://gist.github.com/lxwinspur/6a40abea7330c25e4d49826e890c4be9
The sendEventMsg method is successfully called and the corresponding
message is successfully sent when the D-Bus property value of the sensor
status changes.
print requestMsg Data: 80 02 0a 01 00 00 01 00 01 00 00 00(when calling
sendEventMsg method)

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I9b6d5c1403bfcaa00dbbf478f7d797cc4a40f20d
diff --git a/libpldmresponder/meson.build b/libpldmresponder/meson.build
index a4a8b67..481c82b 100644
--- a/libpldmresponder/meson.build
+++ b/libpldmresponder/meson.build
@@ -21,6 +21,7 @@
   'fru_parser.cpp',
   'fru.cpp',
   '../host-bmc/host_pdr_handler.cpp',
+  '../host-bmc/dbus_to_event_handler.cpp',
   'event_parser.cpp'
 ]