Adjust identifier-naming-hungarian-notation-cfgfile test with
changes for all configs in .clang-tidy to ensure they are really taken
into account.
This is done this way:
- Set all HungarianNotation.* options to cust prefix + their default value.
- Set TreatStructAsClass to true as it defaults to false.
- Because of the TreatStructAsClass change, add a test to check that structs are really checked the same way as classes (see struct StructCase).
Also, TreatStructAsClass was wrongly named in the test's .clang-tidy file
and was fixed (it is in General, not in Options).
Depends on D144431