AT3-485 create stat core executable
- add ska_pst_stat_core executable to implement STAT.CORE functionality
- update ska-pst-smrb dependency to 0.10.5, to acquire changes to protobuf fields and obs_offset for data segments
- update apps documentation for ska-pst-stat
- update ApplicationManager with a base_path for HDF5 monitoring_stats output
- update required keys for beam config, scan config and start scan config
- add support for StatHdf5FileWriter to form a sequence of monitoring stat files with path and filenames that align with ADR-55
- add set/get support for obsutc_start offsets in StatStorage
- connected set/get methods in StatLmcServiceHandler for beam, scan and startscan configurations
- connected the get_scalar_stats
- unified white space conventions (4 -> 2)
- bump patch release to 0.3.6