[HatoholArmPluginGate] Add new virtual function.

onInitiated is an existing virtual function. I use it.
Since there is no "HatoholArmPluginGate::onInitiated()", I'll add a new one.
[HatoholArmPluginGate] Modified to follow the coding roule, and valiable name.
[DBTablesMonitoring] Rename constant name.
[hapi] Modified to follow the coding roule (numXXX).
[HatoholArmPluginGate] Rename function name.

The role of this function(method) is to register trigger and event.
Modify to setPluginConnectStatus.
[hapi] Rename variable name.

HatoholArmPluginWatchPoint -> HatoholArmPluginWatchType.
[hapi] Rename constant name.

HAPI_CMD_SEND_AVAILABLE_TRIGGER -> HAPI_CMD_SEND_HAP_SELF_TRIGGERS