Rewrite ImGuiScene using TerraFX + Add DX12 backend

[Soreepeong]

Changes

Effective

• Frequency of heap allocation has been hugely reduced.
• Memory leak in ImGuiScene has been addressed.
• Number of supported image file types has been increased.

Code

• Integrated deps/ImGuiScene into Dalamud in a namespace Dalamud.ImGuiScene, after a rewrite to avoid allocations and use TerraFX instead of SharpDX.
• Changed image loader from stb_image to WindowsCodecs.
• Duct taping into InterfaceManager to avoid modifying ImGuiScene submodule can stop.
• Dx12Win32Scene has been added.
  • You can use Dx12OnDx11Win32Scene to test it out.
• Incorporates: Add ImDrawList UserCallback support #1526
  • IImGuiScene.SetTexturePipeline, GetTexturePipeline, and ReleaseTexturePipeline has been added. CreateTexturePipeline is on the concrete class for the interface.

Possible future

• Remove PInvoke.User32, PInvoke.Kernel32, and NativeFunctions, and replace them with TerraFX.Interop.Windows.Windows.

Obsoleting

• SharpDX.Direct3D11 is pending for deletion; it has been [Obsolete]d in UiBuilder.
  • Expose DevicePtr instead, so that consumer plugins can wrap the native ID3D11Device* into their wrapper library of choice.
• SharpDX.Mathematics is pending for deletion; it has been [Obsolete]d in VectorExtensions.
  • That's one less autocomplete candidate when you're trying to write Vector3 and stuff..

Notes

ImGui Native Backend cannot be used as-is. ImGui's default DX11 implementation does not push and pop HS/DS/CS in ID3D11DeviceContext, and Win32 implementation deals with IME, which probably will conflict with the game's handling of IME.

[goaaats]

Curious about the note regarding the native DX11 backend, I tried this a while ago and it seemed to be working fine. Was I missing something?

[Soreepeong]

IME completion window would not show, and when multi-viewport is enabled, outside-the-game windows would get considered as not a valid target for IME input; only type English to those.

For HS/DS/CS, it's more of foolproofing. Realistically the game would bind shaders every frame so it won't matter but just in case.

[Soreepeong]

DX11 part works fine; it's restructuring of what has been working so far after all. DX12 part, on the other hand, needs more work. On a moderate load of loading/unloading textures, it causes AVE accessing nullptr during Create(Whatever)Resource calls.

Can't reproduce when DX debug layer is turned off. Will test more. Can't get it to crash anymore without the debug layer.

GPU Based Validation (Preview) enabled from DirectX Control Panel was causing the crash. Disabling that made the crash stop happening. Tested with a sample app that repeatedly creates and frees reserved resources.

[goaaats]

@Soreepeong Did you do any tests on how this interacts with reshade while working on it? Same as before?

[Soreepeong]

This makes reshade unaware of windows created from using viewports.