enum EventTriggers

Pcc Event Triggers.

References from:: PccConfig;

`0`	`SGSN_CHANGE`
`1`	`QOS_CHANGE`
`2`	`RAT_CHANGE`
`4`	`PLMN_CHANGE`
`7`	`IP_CAN_CHANGE`
`12`	`RAI_CHANGE`
`13`	`USER_LOCATION_CHANGE`
`15`	`OUT_OF_CREDIT`
`16`	`REALLOCATION_OF_CREDIT`
`17`	`REVALIDATION_TIMEOUT`
`20`	`DEFAULT_EPS_BEARER_QOS_CHANGE`
`21`	`AN_GW_CHANGE`
`22`	`SUCCESSFUL_RESOURCE_ALLOCATION`
`25`	`UE_TIME_ZONE_CHANGE`
`26`	`TAI_CHANGE`
`27`	`ECGI_CHANGE`
`33`	`USAGE_REPORT`
`39`	`APPLICATION_START`
`40`	`APPLICATION_STOP`
`45`	`ACCESS_NETWORK_INFO_REPORT`
`48`	`CHANGE_OF_UE_PRESENCE_IN_PRESENCE_REPORTING_AREA_REPORT`
`500`	`HOTSPOT_SHARE_START`