Externals / VideoCommon: update imgui to 1.89.7 (and implot to 0.15)

[iwubcode]

This updates imgui to its latest release 1.89.7 and due to breaking changes updates implot to 0.15.

Updating broke our handoff of the IO from QT to ImGui. This review also fixes that and moves us to use AddKeyEvent which is the new recommended way of handling key events.

Finally, I included imgui_demo.cpp as it is pretty handy to be able to see all the demo controls working when doing development. It is left out of compilation with IMGUI_DISABLE_DEMO_WINDOWS but can be enabled if someone wants to reference it.

[iwubcode]

@Pokechu22 - sorry for the ping but would you feel comfortable reviewing this? It looks like you've worked on imgui in the past.

[Pokechu22]

This looks reasonable to me. It'd be nice if we could make imgui a submodule, but I'm not sure how practical it would be to do that with the custom config.

@shuffle2 requested that the demos not be added in #11454 due to compile time concerns, though.

[iwubcode]

@Pokechu22 - looks like we can use the option IMGUI_DISABLE_DEMO_WINDOWS to disable the compile time of the code.

Comment:

// Message to the person tempted to delete this file when integrating Dear ImGui into their codebase:
// Think again! It is the most useful reference code that you and other coders will want to refer to and call.
// Have the ImGui::ShowDemoWindow() function wired in an always-available debug menu of your game/app!
// Also include Metrics! ItemPicker! DebugLog! and other debug features.
// Removing this file from your project is hindering access to documentation for everyone in your team,
// likely leading you to poorer usage of the library.
// Everything in this file will be stripped out by the linker if you don't call ImGui::ShowDemoWindow().
// If you want to link core Dear ImGui in your shipped builds but want a thorough guarantee that the demo will not be
// linked, you can setup your imconfig.h with #define IMGUI_DISABLE_DEMO_WINDOWS and those functions will be empty.
// In another situation, whenever you have Dear ImGui available you probably want this to be available for reference.
// Thank you,
// -Your beloved friend, imgui_demo.cpp (which you won't delete)

Going to put back in the compilation and use that flag.

[iwubcode]

@Pokechu22 - Appreciate you looking this over. I added the C++ interface that imgui ships which supports InputText for std::string which I need in my work. Please have a look and sign off if you think it is ready to go.

[Pokechu22]

Is this static assert no longer correct? DolphinKey is a Common::EnumMap which doesn't do bounds-checking (but it looks like the more relevant thing is that DolphinKey::Z is the last key in the map, and that's less likely to change).

[iwubcode]

Yeah, it's no longer correct. While the key still exists, the number of entries is much much larger (compare with original). There was a big change to 1.87 inputs in imgui from what I understand.

My assumption was that this would be ok because both key_map and dolphin_to_imgui_map are the same types and are both bound by DolphinKey::Z as you mention. If DolphinKeyMap changed both of these maps would need to change as well.

[Pokechu22]

I haven't looked over the changes to imgui itself, but this looks reasonable to me.

[iwubcode]

Looks like this impacted netplay. I will look into reproducing and fix it (from the error guessing it is an unlabeled element).