Update wgpu 0.20 -> 22 && vger 0.3 -> 0.4

[maaku]

With vger having released a new version with wgpu v221, it is time to update rui's dependencies as well. This patch updates the vger dependency to 0.4, and the pegged wgpu version to 22. The only code change required was in the winit logic, which requires you to hint for optimizing for either Performance or MemoryUsage. I chose Performance.

Since many vger applications (including my own) create and manage wgpu devices and render contexts themselves, updating the wgpu dependency is a breaking change for them. I recommend doing a new major release of rui.

[Leif-Rydenfalk]

It is possible to use multiple versions of a crate simultaneously without causing breaking changes. This can be achieved by explicitly specifying different versions of the same crate in the Cargo.toml file. For example, in the case of the wgpu crate, we can define multiple versions as follows:

[dependencies]
wgpu_20 = { package = "wgpu", version = "0.20" }
wgpu_22 = { package = "wgpu", version = "0.22" }

This approach allows the user to select which version to use by enabling the appropriate feature.

For more information, see the original discussion on Stack Overflow.

Edit: Found a example of this being used here: Github - egui theme