test(topology): add quadrilaterals test

Test file included in main test/runtests.jl
Tests quadrilateral element topology

test/topology/test_quadrilaterals.jl

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+# This file is a part of JuliaFEM.
+# License is MIT: see https://github.com/JuliaFEM/JuliaFEM.jl/blob/master/LICENSE.md
+
+using JuliaFEM
+using Test
+using StaticArrays
+
+@testset "Quadrilateral Elements" begin
+    @testset "Quadrilateral{4}" begin
+        @test nnodes(Quadrilateral{4}()) == 4
+        @test dim(Quadrilateral{4}()) == 2
+        @test nvertices(Quadrilateral{4}()) == 4
+        @test nedges(Quadrilateral{4}()) == 4
+        @test nfaces(Quadrilateral{4}()) == 1
+        
+        # Entity counts
+        @test nentities(Quadrilateral{4}, Vertex) == 4
+        @test nentities(Quadrilateral{4}, Edge) == 4
+        @test nentities(Quadrilateral{4}, Face) == 1
+        @test nentities(Quadrilateral{4}, Cell) == 1
+    end
+    
+    @testset "Quadrilateral{8}" begin
+        @test nnodes(Quadrilateral{8}()) == 8
+        @test nvertices(Quadrilateral{8}()) == 4  # Same topology
+        @test nedges(Quadrilateral{8}()) == 4
+        @test nentities(Quadrilateral{8}, Edge) == 4
+    end
+    
+    @testset "Quadrilateral{9}" begin
+        @test nnodes(Quadrilateral{9}()) == 9
+        @test nvertices(Quadrilateral{9}()) == 4  # Same topology
+        @test nedges(Quadrilateral{9}()) == 4
+        @test nentities(Quadrilateral{9}, Edge) == 4
+    end
+end