DB IDO: Add endpoint_name to programstatus table

refs #6827
refs #6203
DB IDO: Add 'enable_ha' configuration flag

This feature is true by default. If disabled all cluster nodes in a high
availability zone will write to their own local database.

TODO: documentation, tests.

refs #6827
refs #6203
DB IDO: Delay connection in HA RunOnce mode

refs #6827
refs #6203
DB IDO: Add documentation for HA functionality

refs #6827
refs #6203
DB IDO: Add failover_timeout attribute

refs #6827
Merge branch 'feature/ido-ha-6827'

fixes #6827
refs #6203
DB IDO: Fix failover_timeout config validator

refs #6827
Implement support for writing the icinga2.debug file

refs #6702
Add debug hints for attributes

refs #6702
Add Python module for the icinga2.debug file

refs #6702