Use Self everywhere (#3787)

This turns on the clippy lint
[`clippy::use_self`](https://rust-lang.github.io/rust-clippy/v0.0.212/index.html#use_self)
and fixes it everywhere.

crates/eframe/src/native/glow_integration.rs

@@ -962,7 +962,7 @@ impl GlutinWindowContext {
         // help us start from scratch again if we fail context creation and go back to preferEgl or try with different config etc..
         // https://github.com/emilk/egui/pull/2541#issuecomment-1370767582
 
-        let mut slf = GlutinWindowContext {
+        let mut slf = Self {
             egui_ctx: egui_ctx.clone(),
             swap_interval,
             gl_config,

crates/eframe/src/native/wgpu_integration.rs

@@ -492,7 +492,7 @@ impl WgpuWinitRunning {
         #[cfg(feature = "puffin")]
         puffin::GlobalProfiler::lock().new_frame();
 
-        let WgpuWinitRunning {
+        let Self {
             app,
             integration,
             shared,