Add HarnessBuilder::with_render_options() (closes #7630) (#8060)

Allows to override the default `PREDICTABLE` render options, e.g. if
it's desired to create snapshots with the exact texture options used by
the app.

See #7630 for details / examples.

crates/egui_kittest/src/wgpu.rs

@@ -58,7 +58,10 @@ pub fn default_wgpu_setup() -> egui_wgpu::WgpuSetup {
     egui_wgpu::WgpuSetup::CreateNew(setup)
 }
 
-pub fn create_render_state(setup: WgpuSetup) -> egui_wgpu::RenderState {
+pub fn create_render_state(
+    setup: WgpuSetup,
+    options: egui_wgpu::RendererOptions,
+) -> egui_wgpu::RenderState {
     // No display handle needed for headless testing — we don't present to a window.
     let instance = pollster::block_on(setup.new_instance());
 
@@ -69,7 +72,7 @@ pub fn create_render_state(setup: WgpuSetup) -> egui_wgpu::RenderState {
         },
         &instance,
         None,
-        egui_wgpu::RendererOptions::PREDICTABLE,
+        options,
     ))
     .expect("Failed to create render state")
 }
@@ -89,14 +92,17 @@ impl WgpuTestRenderer {
     /// Create a new [`WgpuTestRenderer`] with the default setup.
     pub fn new() -> Self {
         Self {
-            render_state: create_render_state(default_wgpu_setup()),
+            render_state: create_render_state(
+                default_wgpu_setup(),
+                egui_wgpu::RendererOptions::PREDICTABLE,
+            ),
         }
     }
 
     /// Create a new [`WgpuTestRenderer`] with the given setup.
     pub fn from_setup(setup: WgpuSetup) -> Self {
         Self {
-            render_state: create_render_state(setup),
+            render_state: create_render_state(setup, egui_wgpu::RendererOptions::PREDICTABLE),
         }
     }
 
@@ -115,6 +121,13 @@ impl WgpuTestRenderer {
         );
         Self { render_state }
     }
+
+    /// Create a new [`WgpuTestRenderer`] with custom render options.
+    pub fn with_render_options(options: egui_wgpu::RendererOptions) -> Self {
+        Self {
+            render_state: create_render_state(default_wgpu_setup(), options),
+        }
+    }
 }
 
 impl crate::TestRenderer for WgpuTestRenderer {