[HatoholDBUtils] Add a new class to move some helper method in DBClientZabbix.

These two methods are moved.
- transformEventsToHatoholFormat
- transformEventItemGroupToEventInfo
[HatoholDBUtils] Move methods to transform hosts.

The moved methods:
- transformGroupItemGroupToHostgroupInfo
- transformGroupsToHatoholFormat
[HatoholDBUtils] Use an abstract type: ServerIdType.
[HatoholDBUtils] Move methods to transform hosts.

The moved methods:
- transformHostsGroupsItemGroupToHatoholFormat
- transformHostsGroupsToHatoholFormat
[HatoholDBUtils] Move methods to transform hosts.

The moved methods:
- transformHostsItemGroupToHatoholFormat
- transformHostsToHatoholFormat
[ZabbixAPI] Add a new method only to get necessary applications.
[HatoholDBUtils] Move methods to transform items.
[HatoholDBUtils] Move some method to protected.
[HostInfoCache] Add const qualifier.
[ArmZabbixAPI] Transform triggers without DBClientZabbix.
[ArmZabbixAPI] Remove the use of DBClientZabbix.
[HatoholArmPluginGate] Remove the use of DBClientZabbix.
[ArmZabbixAPI] Remove unused methods.
[ArmZabbixAPI] Remove an unused method: updateApplications().
[ArmZabbixAPI] Remove an unused method: addApplicationDataToDB().
Revert "[ArmZabbixAPI] Remove an unused method: updateApplications()."

This reverts commit 5e4cee24c198834a2bb61e4bc4bb1a2db89cff85.
[ArmZabbixAPI] Use an DBClientHatohol instance in the private context.
[ArmZabbixAPI] Remove unused methods.
[ArmZabbixAPI] Remove a member from the private context.
[ArmZabbixAPI] Align variables.