Iterator ranges: astyle-safe trait members; reserve in the test helper

The byte check and the container match are static constexpr members
instead of integral_constant arguments and a default template argument
with comparisons, which astyle spaced out.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

tests/src/unit-deserialization.cpp

@@ -1433,6 +1433,7 @@ template<typename T>
 std::vector<T> bytes_as(const std::string& text)
 {
     std::vector<T> result;
+    result.reserve(text.size());
     for (const char c : text)
     {
         result.push_back(static_cast<T>(c));