Use iterators in FromJson to avoid copies - #41641

This PR refactors shared JSON deserialization helpers to support parsing directly from iterator ranges, enabling callers to avoid allocating/copying buffers into temporary std::strings before parsing. It also updates WSLc image-import progress parsing to use the new iterator-based API.

Changes:

• Added an iterator-range FromJson overload and routed existing const char* / const wchar_t* overloads through it.
• Updated WSLCSession::ImportImageImpl progress parsing to parse JSON directly from the received buffer iterators.

Suppressed comments (2)

src/shared/inc/JsonUtils.h:82

• const std::string_view value{First, Last}; depends on the C++23 iterator-range constructor and on Iterator being contiguous; this is likely to break builds or callers that pass non-contiguous iterators. Since this is only used on the exception path, consider materializing a std::string from the iterator range for logging/error text instead.

        const std::string_view value{First, Last};

#ifdef WIN32

        THROW_HR_WITH_USER_ERROR_MSG(

src/shared/inc/JsonUtils.h:101

• FromJson(const char* Value) uses strlen(Value) but this header doesn’t include <cstring> (and on Windows stringshared.h doesn’t include it either), so this can be a fragile/implicit dependency. Prefer std::char_traits<char>::length(Value) (available via <string>) to keep the header self-contained.

T FromJson(const char* Value)
{
    return FromJson<T, TJson>(Value, Value + strlen(Value));
}

• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Lite