[CMake] Replaced CMAKE_SOURCE_DIR with PROJECT_SOURCE_DIR.

Applications/DataExplorer/CMakeLists.txt

Applications/Utils/OGSFileConverter/CMakeLists.txt

Applications/Utils/SWMMConverter/CMakeLists.txt

Documentation/Doxyfile.in

ThirdParty/CMakeLists.txt

scripts/cmake/CMakeSetup.cmake

scripts/cmake/ConanSetup.cmake

scripts/cmake/Coverage.cmake

scripts/cmake/ExternalProjectCatalyst.cmake

scripts/cmake/ExternalProjectVtk.cmake

scripts/cmake/Find.cmake

scripts/cmake/MetisSetup.cmake

scripts/cmake/Web.cmake

scripts/cmake/packaging/ArchiveTestdata.cmake

scripts/cmake/packaging/Pack.cmake

scripts/cmake/packaging/PackagingLinux.cmake

scripts/cmake/packaging/PackagingMac.cmake

scripts/cmake/packaging/PackagingWin.cmake

scripts/cmake/test/AddTest.cmake