Merge branch 'XdmfLib' into 'master'

Add Xdmf library

See merge request ogs/ogs!3249

.gitmodules

@@ -49,3 +49,6 @@
 [submodule "ThirdParty/xdmfdiff"]
 	path = ThirdParty/xdmfdiff
 	url = https://gitlab.opengeosys.org/ogs/xdmfdiff.git
+[submodule "ThirdParty/xdmf"]
+	path = ThirdParty/xdmf
+	url = https://gitlab.opengeosys.org/ogs/xdmflib.git

scripts/cmake/SubmoduleSetup.cmake

@@ -18,6 +18,7 @@ set(REQUIRED_SUBMODULES
     ThirdParty/spdlog
     ThirdParty/tclap
     ThirdParty/tetgen
+    ThirdParty/xdmf
     ${OGS_ADDITIONAL_SUBMODULES_TO_CHECKOUT}
 )
 if(BUILD_TESTING)