Messages with an icon and no text (such as in the game start sequence) had an oversized margin due to ImGui adding padding for an empty string.

OSD messages with an icon and text will display the text to the right of the icon instead of below it.

Achievement badges/icons are refactored into the type CustomTextureData::ArraySlice::Level as that is the data type images loaded from the filesystem will be. This includes everything that uses the badges in the Qt UI and OnScreenDisplay, and similarly removes the OSD::Icon type because Level already contains that information.

Co-authored-by: TellowKrinkle <tellowkrinkle@gmail.com>

SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.

-They might have never drawn if DrawMessages wasn't called before they actually expired
-Their fade was wrong if the duration of the message was less than the fade time

This makes them much more useful for debugging, I know there might be other means
of debugging like logs and imgui, but this was the simplest so that's what I used.
If you want to print the same message every frame, but with a slightly different value
to see the changes, it now work.

To compensate for the fact that they are now always rendered once,
so on start up a lot of old messages (printed while the emulation was off) could show up,
I've added a "drop" time, which means if a msg isn't rendered for the first
time within that time, it will be dropped and never rendered.