[MACsecMgr]: Add MACsec Manager (sonic-net#1475)

Add MACsec Manager for MACsec feature.
MACsecMgr is a daemon in MACsec container, that receives the message from CONFIG DB and uses wpa_cli instructions to manage the functionality of MACsec in the specified port. The below figure is the flow chart of MACsecMgr which shows the MACsec profile management according to MACsec Profile Table and the functionality of MACsec in the specified port according to PortTable.
The main functions are defined in class MACsecMgr as follow
```
    task_process_status removeProfile(const std::string & profile_name, const TaskArgs & profile_attr);
    task_process_status loadProfile(const std::string & profile_name, const TaskArgs & profile_attr);
    task_process_status enableMACsec(const std::string & port_name, const TaskArgs & port_attr);
    task_process_status disableMACsec(const std::string & port_name, const TaskArgs & port_attr);
```

The HLD of MACsec Manager is at [MACsec HLD](https://github.com/Azure/SONiC/blob/master/doc/macsec/MACsec_hld.md#341-macsec-mgr)

Signed-off-by: Ze Gan <ganze718@gmail.com>

.gitignore

@@ -51,6 +51,7 @@ cfgmgr/vrfmgrd
 cfgmgr/vxlanmgrd
 cfgmgr/natmgrd
 cfgmgr/sflowmgrd
+cfgmgr/macsecmgrd
 fpmsyncd/fpmsyncd
 gearsyncd/gearsyncd
 mclagsyncd/mclagsyncd

cfgmgr/Makefile.am

@@ -3,7 +3,7 @@ CFLAGS_SAI = -I /usr/include/sai
 LIBNL_CFLAGS = -I/usr/include/libnl3
 LIBNL_LIBS = -lnl-genl-3 -lnl-route-3 -lnl-3
 
-bin_PROGRAMS = vlanmgrd teammgrd portmgrd intfmgrd buffermgrd vrfmgrd nbrmgrd vxlanmgrd sflowmgrd natmgrd coppmgrd tunnelmgrd
+bin_PROGRAMS = vlanmgrd teammgrd portmgrd intfmgrd buffermgrd vrfmgrd nbrmgrd vxlanmgrd sflowmgrd natmgrd coppmgrd tunnelmgrd macsecmgrd
 
 cfgmgrdir = $(datadir)/swss
 
@@ -81,3 +81,7 @@ tunnelmgrd_CFLAGS = $(DBGFLAGS) $(AM_CFLAGS) $(CFLAGS_COMMON) $(CFLAGS_SAI)
 tunnelmgrd_CPPFLAGS = $(DBGFLAGS) $(AM_CFLAGS) $(CFLAGS_COMMON) $(CFLAGS_SAI)
 tunnelmgrd_LDADD = -lswsscommon
 
+macsecmgrd_SOURCES = macsecmgrd.cpp macsecmgr.cpp $(top_srcdir)/orchagent/orch.cpp $(top_srcdir)/orchagent/request_parser.cpp shellcmd.h
+macsecmgrd_CFLAGS = $(DBGFLAGS) $(AM_CFLAGS) $(CFLAGS_COMMON) $(CFLAGS_SAI)
+macsecmgrd_CPPFLAGS = $(DBGFLAGS) $(AM_CFLAGS) $(CFLAGS_COMMON) $(CFLAGS_SAI)
+macsecmgrd_LDADD = -lswsscommon