Gizmo: Add anti aliasing to transform constraints

Transform constraints were being drawn on screen without anti-aliasing,
now fixed to make them look smoother.
See #107038

Adding a comparison of before and after the change

Pull Request: https://projects.blender.org/blender/blender/pulls/107394

source/blender/editors/transform/transform_constraints.c

@@ -778,7 +778,14 @@ static void drawLine(
 
   uint pos = GPU_vertformat_attr_add(immVertexFormat(), "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
 
-  immBindBuiltinProgram(GPU_SHADER_3D_UNIFORM_COLOR);
+  float viewport[4];
+  GPU_viewport_size_get_f(viewport);
+  GPU_blend(GPU_BLEND_ALPHA);
+
+  immBindBuiltinProgram(GPU_SHADER_3D_POLYLINE_UNIFORM_COLOR);
+  immUniform2fv("viewportSize", &viewport[2]);
+  immUniform1f("lineWidth", U.pixelsize * 2.0f);
+
   immUniformColor3ubv(col2);
 
   immBegin(GPU_PRIM_LINES, 2);