Update MSRV to Rust 1.70.0 (#3310)

* Update to Rust 1.70

* Fix renamed clippy lint

* Use let-else more

* Code cleanup

* Remove derelict Safety comments

* Enable more clippy lints

crates/eframe/src/web/input.rs

@@ -35,7 +35,6 @@ pub fn pos_from_touch_event(
         // search for the touch we previously used for the position
         // (unfortunately, `event.touches()` is not a rust collection):
         (0..event.touches().length())
-            .into_iter()
             .map(|i| event.touches().get(i).unwrap())
             .find(|touch| egui::TouchId::from(touch.identifier()) == *touch_id_for_pos)
     } else {

crates/eframe/src/web/web_painter_wgpu.rs

@@ -148,9 +148,7 @@ impl WebPainter for WebPainterWgpu {
     ) -> Result<(), JsValue> {
         let size_in_pixels = [self.canvas.width(), self.canvas.height()];
 
-        let render_state = if let Some(render_state) = &self.render_state {
-            render_state
-        } else {
+        let Some(render_state) = &self.render_state else {
             return Err(JsValue::from_str(
                 "Can't paint, wgpu renderer was already disposed",
             ));