Fix panic in examples using argh on the web (#11513)

# Objective

Fixes #11503

## Solution

Use an empty set of args on the web.

## Discussion

Maybe in the future we could wrap this so that we can use query args on
the web or something, but this was the minimum changeset I could think
of to keep the functionality and make them not panic on the web.

examples/stress_tests/bevymark.rs

@@ -94,7 +94,11 @@ impl FromStr for Mode {
 const FIXED_TIMESTEP: f32 = 0.2;
 
 fn main() {
+    // `from_env` panics on the web
+    #[cfg(not(target_arch = "wasm32"))]
     let args: Args = argh::from_env();
+    #[cfg(target_arch = "wasm32")]
+    let args = Args::from_args(&[], &[]).unwrap();
 
     App::new()
         .add_plugins((

examples/stress_tests/many_buttons.rs

@@ -42,7 +42,12 @@ struct Args {
 
 /// This example shows what happens when there is a lot of buttons on screen.
 fn main() {
+    // `from_env` panics on the web
+    #[cfg(not(target_arch = "wasm32"))]
     let args: Args = argh::from_env();
+    #[cfg(target_arch = "wasm32")]
+    let args = Args::from_args(&[], &[]).unwrap();
+
     let mut app = App::new();
 
     app.add_plugins((

examples/stress_tests/many_cubes.rs

@@ -66,7 +66,11 @@ impl FromStr for Layout {
 }
 
 fn main() {
+    // `from_env` panics on the web
+    #[cfg(not(target_arch = "wasm32"))]
     let args: Args = argh::from_env();
+    #[cfg(target_arch = "wasm32")]
+    let args = Args::from_args(&[], &[]).unwrap();
 
     App::new()
         .add_plugins((

examples/stress_tests/many_foxes.rs

@@ -33,7 +33,11 @@ struct Foxes {
 }
 
 fn main() {
+    // `from_env` panics on the web
+    #[cfg(not(target_arch = "wasm32"))]
     let args: Args = argh::from_env();
+    #[cfg(target_arch = "wasm32")]
+    let args = Args::from_args(&[], &[]).unwrap();
 
     App::new()
         .add_plugins((

examples/ui/text_wrap_debug.rs

@@ -19,7 +19,12 @@ struct Args {
 }
 
 fn main() {
+    // `from_env` panics on the web
+    #[cfg(not(target_arch = "wasm32"))]
     let args: Args = argh::from_env();
+    #[cfg(target_arch = "wasm32")]
+    let args = Args::from_args(&[], &[]).unwrap();
+
     let window = if let Some(scale_factor) = args.scale_factor {
         Window {
             resolution: WindowResolution::default().with_scale_factor_override(scale_factor),