test(topology): add entity dimensions test

Test file included in main test/runtests.jl
Tests topological entity dimension properties

test/topology/test_entity_dimensions.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
+
+@testset "Entity Dimensions" begin
+    # 1D elements
+    @test dim(Segment{2}()) == 1
+    @test dim(Segment{3}()) == 1
+    
+    # 2D elements
+    @test dim(Triangle{3}()) == 2
+    @test dim(Triangle{6}()) == 2
+    @test dim(Quadrilateral{4}()) == 2
+    @test dim(Quadrilateral{9}()) == 2
+    
+    # 3D elements
+    @test dim(Tetrahedron{4}()) == 3
+    @test dim(Tetrahedron{10}()) == 3
+    @test dim(Hexahedron{8}()) == 3
+    @test dim(Hexahedron{27}()) == 3
+    @test dim(Pyramid{5}()) == 3
+    @test dim(Wedge{6}()) == 3
+    @test dim(Wedge{15}()) == 3
+end