Fix WebGL mode for Adreno GPUs (bevyengine#8508)

# Objective

- This fixes a crash when loading shaders, when running an Adreno GPU
and using WebGL mode.
- Fixes bevyengine#8506 
- Fixes bevyengine#8047

## Solution

- The shader pbr_functions.wgsl, will fail in apply_fog function, trying
to access values that are null on Adreno chipsets using WebGL, these
devices are commonly found in android handheld devices.

---------

Co-authored-by: Carter Anderson <[email protected]>
Co-authored-by: François <[email protected]>

crates/bevy_pbr/src/render/light.rs

@@ -216,6 +216,12 @@ pub struct GpuLights {
 
 // NOTE: this must be kept in sync with the same constants in pbr.frag
 pub const MAX_UNIFORM_BUFFER_POINT_LIGHTS: usize = 256;
+
+//NOTE: When running bevy on Adreno GPU chipsets in WebGL, any value above 1 will result in a crash
+// when loading the wgsl "pbr_functions.wgsl" in the function apply_fog.
+#[cfg(all(feature = "webgl", target_arch = "wasm32"))]
+pub const MAX_DIRECTIONAL_LIGHTS: usize = 1;
+#[cfg(any(not(feature = "webgl"), not(target_arch = "wasm32")))]
 pub const MAX_DIRECTIONAL_LIGHTS: usize = 10;
 #[cfg(any(not(feature = "webgl"), not(target_arch = "wasm32")))]
 pub const MAX_CASCADES_PER_LIGHT: usize = 4;