Update to Dear ImGui 1.90.1

[whitequark]

This is my first imgui-rs PR and my first time using Dear ImGui, so please forgive me if I've not quite followed the conventions of these bindings right. A few mechanisms were deprecated; none of them seem especially commonly used to me, so I haven't added any compatibility shims, and instead tried to stay as close to the upstream as possible.

I've done my best to keep the newly introduced entities (enums, mainly) complete but I haven't exposed all of them in the Rust API as this is a lot of work and the added APIs seem niche. I don't think I have the time to add them.

The motivation for this PR is proper HiDPI support, which was merged in 1.90. It was harmless to upgrade to 1.90.1, so I've done that as well.

[salvatorebenedetto]

Hey @whitequark, thanks a lot for doing this. I also recently asked for it in #787 which has resizable window.

I'm not a maintainer but it would probably help maintainers if you can write what tests you executed to validate your upgrade. Thanks again for doing this. I hope it gets merged soon.

CC: @sanbox-irl who might be interested in this.

[whitequark]

I'm not a maintainer but it would probably help maintainers if you can write what tests you executed to validate your upgrade.

I ran a few of the examples provided with all four of the possible Dear ImGui branches (all combinations of freetype and docking) and verified that they run reasonably well. I also checked that my own Dear ImGui based application works well.

[sanbox-irl]

Hi all! Sorry, the game I work on (fields of mistria) is nearing its release -- I'll try to take a look sooner (I'm keeping it high in my github notifications), but it's pinching my time pretty severely. I appreicate your work!

[whitequark]

No worries! That looks like a really cute game.

[salvatorebenedetto]

Any updates here @sanbox-irl ? Is there any other maintainer other than you who can take a look at this? Thanks.

[whitequark]

Note that I've decided to switch to egui since (the ergonomics of dear imgui and to a lesser extent imgui-rs were too impairing for my project) so I'm not going to be updating this PR further.

[sanbox-irl]

Closing this in favor of #795, which pulled in your changes. Thank you very much! As per your last message, I didn't think you'd want an extended back-and-forth, so I copied over much of your work and updated past to 1.91. You'll be thanked and credited in the Git comments and the release CI!

[whitequark]

Thanks, much appreciated!