* Added <autogenerated> in cs generator file header comment
#4287

* CS: Added xml-correct file header comment including "<auto-generated>...</auto-generated>"
code_generators.cpp: FlatBuffersGeneratedWarning() function replaced by compile time constant "GeneratedWarning"
 also removed extra newlines at end of GeneratedWarning to be able to generate a xml well formed file comment for cs files
#4291

* code_generators: Changed static string GeneratedWarning back to function FlatBuffersGeneratedWarning()
#4291

* Added modified Unit-Test files
#4291

* idl_gen_general: Add autogenerated only in C# code
#4291