RetroAchievements - Fixed Leaderboard Scored message format

[LillyJadeKatrin]

Refactored the message displayed when a leaderboard is submitted to so that it properly generates and uses a FormattedValue.

[AdmiralCurtiss]

Is this guaranteed to return a nullterminated string? I'm not seeing anything indicating that in the documentation. In fact, by that I would expect:

FormattedValue value;
int length = rc_runtime_format_lboard_value(value.data(), FORMAT_SIZE, runtime_event->value, m_game_data.leaderboards[ix].format);
std::string_view str(value.data(), std::min(value.size(), static_cast<size_t>(length)));
OSD::AddMessage(fmt::format("Scored {} on leaderboard: {}", str, m_game_data.leaderboards[ix].title),

[LillyJadeKatrin]

Under the hood, every call to both rc_runtime_format_lboard_value and rc_runtime_format_achievement_measured calls sprintf on a string literal, which to my understanding should always nullterminate.

[LillyJadeKatrin]

Also, the maximum returned size of a formatted string can be 21 characters, and I was recommended to use 24 as a nice round number, so there's space allocated for the terminator.