Check type of launch config (#2125)

* Check type of launch config

* fix cargo check

* compile when using an explicit platform with other platforms enabled

* fix formatting

* fix overlapping TryIntoConfig implementations

* fix desktop headless tests

---------

Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

examples/calculator.rs

@@ -13,7 +13,7 @@ use dioxus::html::input_data::keyboard_types::Key;
 use dioxus::prelude::*;
 
 fn main() {
-    LaunchBuilder::new()
+    LaunchBuilder::desktop()
         .with_cfg(desktop!({
             use dioxus::desktop::{Config, LogicalSize, WindowBuilder};
             Config::new().with_window(

examples/custom_html.rs

@@ -4,7 +4,7 @@
 use dioxus::prelude::*;
 
 fn main() {
-    LaunchBuilder::desktop()
+    LaunchBuilder::new()
         .with_cfg(
             dioxus::desktop::Config::new().with_custom_index(
                 r#"

examples/suspense.rs

@@ -15,14 +15,14 @@ use dioxus::desktop::{Config, LogicalSize, WindowBuilder};
 use dioxus::prelude::*;
 
 fn main() {
-    LaunchBuilder::desktop()
-        .with_cfg(
+    LaunchBuilder::new()
+        .with_cfg(desktop! {
             Config::new().with_window(
                 WindowBuilder::new()
                     .with_title("Doggo Fetcher")
                     .with_inner_size(LogicalSize::new(600.0, 800.0)),
-            ),
-        )
+            )
+        })
         .launch(app)
 }