MSVC 2017 15.7 contains a bug where constant initialization no longer
takes place for objects with constructors marked constexpr such as
once_flag. This leaves once_flag susceptible to dynamic initialization
order problems and causes some singleton instances to be constructed
incorrectly. We put back our correct implementation (with some cleanup)
and await a fix from MS.
Refs #0

and improve the default user properties file.

re #23102

re #23102

re #23102

re #23102

re #23102

This commit removes the validation error for workspace groups which results in an error shown on the GUI. Instead validation is skipped for group workspace inputs to the efficiencies workspace property. The reason for this is that validateInputs is not called when the algorithm is run from a script. Therefore we get the same behaviour from the gui and the script, where the algorithm will be called on each member of the group initially. This could be improved further but is out of scope of this PR.

Re #23061

This fix adds a guard against workspace groups in the PolarizationCorrectionWildes algorithm's validateInputs. The algorithm dialog lets you select a workspace group if all of its members are valid matrix workspaces; however, a group is not valid input for this property.

Re #23061