Modernize/cleanup UT code
- simplify interaction between stripflip() and xInverted()
- add const where appropriate
- prefer C++ headers over C headers (eg. cstddef instead of stddef.h)
- prefer std::memcpy over assignment to a reinterpret_cast-ed object (alignment!)
- prefer inherited constructors instead of explictly forwarding constructructors
- prefer string_view over const std::string&
- prefer pragma once over header guards
- make sure order of include files does not matter
- let clang-format order the include files
- remove unneccessary mutable qualifiers
- avoid unneccessary copies
- prefer standalone functions in anonymous namespace over member functions
- remove unneccessary destructors
- prefer boost::flat_map over GaudiUtils::VectorMap as it supports transparant lookup
- prefer charconv and error check over stoul and exception handling, as it also allows the use of string_view
- prefer member initialization on declaration
- define trivial inline functions at their point of declaration
- prefer monadic StatusCode functionality
- do not compare bool to literal
trueorfalsein conditionals - move operator<< out of global namespace, make friend instead, change argument type from pointer to object
- leave [[deprecated]] version in global namespace which takes pointer
- move use of UTNames() out of UTDigit.h into UTDigit.cpp to keep it away from cling, which doesn't like boost::flat_map
- update CMakeLists to reflect that DigitEvent now has a (tiny) library
- remove UTNames and UTCluster from dictionary
must be applied in conjunction with Lbcom!538 (merged), Boole!328 (merged), Rec!2323 (merged)