Fix out of bounds read with kParseValidateEncodingFlag

CMakeLists: include path fix + compatibility.

Fix parsing 0.184467440737095516159 with kParseFullPrecisionFlag

Guard against max being macros in schema.h

Cpp version depended if constexpr schema.h

Cpp depended if constexpr pointer.h

Increase CMake minimum version to 3.5 (fixes #2159)

Fix endif condition to match `NOT MSVC and VALGRIND_FOUND`.

add test for sso optimized string

Fix issue 2307

Fix bug when parsing NaN, Inf with fraction or exponent parts (fixes #2299)

rapidjson.h: add forgotten ppc64 case

Add RAPIDJSON_BUILD_CXX20 option

fix Visual Studio 2022 (using /std:c++20) warning warning C5232: in C++20 this comparison calls ... recursively

tests: Only run valgrind tests if valgrind was found