Support storage of output from "MAP_INPUT" functor that returns "std::optional<T>" or "std::nullopt"
This MR supports storage of output of MAP_INPUT functor that returns std::optional<T> or std::nullopt.
In this regard, it adds a helper class LHCb::FTuple::InvalidValue to store default (invalid) value when std::nullopt is returned. Idea arose from discussions with @graven in this MR `(Rec!2666 (closed)) (particularly in this comment).
Also support tupling of SIMDWrapper::scalar::float_v, avoid explicit std::any declaration, fix to fill_ method of non-symmetric matrices and clean-up obsolete header file inclusion.
This MR is related to (but not dependent on): Rec!2666 (closed)
Edited by Abhijit Mathad