Upgrade Raylib to 6.0 (#337)

* Updated target to Raylib 6 + synced invoke called with the changes in C. [WARNING: Breaking changes!]

* Added severial examples. Corrected towards the correct return type and add utilities to prevent working with pointers

* Additional resources from the Raylib repo.

* Fixed additional pinvokes to match with the new raylib bindings. [Warning breaking changes!]

* Fixing the QOL utils

* Fixing the Mesh struct

* Applying changes after review. Merged resources.LICENSE + raylib-cs.Native.csproj only targets dotnet8

* Updated README to reflect .NET 10 and Raylib 6 compatibility changes.

* Updated shader colors, adjusted car model scale, disabled HDR in SkyboxDemo, and fixed camera mode assignment. Removed unused `Capacity` field in FilePathList struct.

* Improved XML comments for consistency, fixed spacing and formatting across examples, added new resources to `resources.LICENSE`.

* Updated XML comment for `GetDirectoryFileCountEx` to clarify behavior and filtering options.

* Updated and clarified XML comments for methods and parameters, improved naming consistency, and refined shader-related functions. Renamed enums in `Shader.cs` for so it is inline with the upstream.

* Improved XML comments for clarity and consistency in `Model.cs` and `Mesh.cs`, updated method and variable names for better readability, and adjusted logic in span creation methods.

* Corrected XML comment capitalization in `Model.cs`.

---------

Co-authored-by: Meatcorps <info@meatcorps.nl>

Examples/resources/shaders/glsl120/sdf.fs

@@ -0,0 +1,23 @@
+#version 120
+
+// Input vertex attributes (from vertex shader)
+varying vec2 fragTexCoord;
+varying vec4 fragColor;
+
+// Input uniform values
+uniform sampler2D texture0;
+uniform vec4 colDiffuse;
+
+// NOTE: Add your custom variables here
+const float smoothing = 1.0/16.0;
+
+void main()
+{
+    // Texel color fetching from texture sampler
+    // NOTE: Calculate alpha using signed distance field (SDF)
+    float distance = texture2D(texture0, fragTexCoord).a;
+    float alpha = smoothstep(0.5 - smoothing, 0.5 + smoothing, distance);
+
+    // Calculate final fragment color
+    gl_FragColor = vec4(fragColor.rgb, fragColor.a*alpha);
+}