Previously the decoder would create garbage time of flight values.

This test ensures that the Kafka event decoder returns correct ToF
values for a known message.

When starting the Kafka event stream decoder if OpenMP is not available
then show a warning.

Without OpenMP the parallel insertion cannot happen and the
optimisations added will not show sufficient performance improvement.

This is based on the prototype derived from the meeting at the DMSC last December.

The workflow is as follows:
  - Pool all events received from the Kafka stream into a single buffer
  - When the buffer is to be flushed (i.e. events populated in the EventWorkspace):
    - Parallel sort the event buffer by the detector ID/workspace index
    - Determine group boundaries
    - Parallel insert events into EventWorkspace

Also included is the optimisation of using a spec to ID mapping based on
a vector rather than map.
This provides better performance during the initial event buffering
(where this lookup is made).

Initial benchamrking shows 25M events is a intermediate buffer threshold
for LOKI (9 banks) at 10^7 events per second.
This manages to maintain well over 14Hz pulse rate (with no post
processing).

- delete unused includes
- prefer getPropertyValueAsType instead of casting a string to ..

Refs #25580

Framework/LiveData/src/Kafka/private/Schema/flatbuffers/base.h had a check for C++11 compatiblity which caused cppcheck to skip some files in LiveData. The #ifdefs were removed since we now use C++14 for building Mantid.

Re #22912

re #15452

The stream capture runs in a separate thread and registering
new callbacks while the capture process is running will cause
a race condition if not protected by a mutex.

This was replaced wholesale recently but missed in a new file
that was created and merged after the changes.