Create custom cursor with directly with event loop

Replace the `CustomCursorBuilder` with the `CustomCursorSource` and
perform the loading of the cursor via the
`EventLoop::create_custom_cursor` instead of passing it to the builder
itself.

This follows the `EventLoop::create_window` API.

src/event_loop.rs

@@ -19,7 +19,7 @@ use std::time::{Duration, Instant};
 use web_time::{Duration, Instant};
 
 use crate::error::{EventLoopError, OsError};
-use crate::window::{Window, WindowAttributes};
+use crate::window::{CustomCursor, CustomCursorSource, Window, WindowAttributes};
 use crate::{event::Event, monitor::MonitorHandle, platform_impl};
 
 /// Provides a way to retrieve events from the system and from the windows that were registered to
@@ -299,6 +299,14 @@ impl<T> EventLoop<T> {
             platform_impl::Window::new(&self.event_loop.window_target().p, window_attributes)?;
         Ok(Window { window })
     }
+
+    /// Create custom cursor.
+    pub fn create_custom_cursor(&self, custom_cursor: CustomCursorSource) -> CustomCursor {
+        self.event_loop
+            .window_target()
+            .p
+            .create_custom_cursor(custom_cursor)
+    }
 }
 
 #[cfg(feature = "rwh_06")]
@@ -359,6 +367,11 @@ impl ActiveEventLoop {
         Ok(Window { window })
     }
 
+    /// Create custom cursor.
+    pub fn create_custom_cursor(&self, custom_cursor: CustomCursorSource) -> CustomCursor {
+        self.p.create_custom_cursor(custom_cursor)
+    }
+
     /// Returns the list of all the monitors available on the system.
     #[inline]
     pub fn available_monitors(&self) -> impl Iterator<Item = MonitorHandle> {