Change platform name to pugs (Parallel Unstructured Grid Solver)

.gitlab-ci.yml

CMakeLists.txt

CONTRIBUTING.md

README.md

cmake/ClangFormatProcess.cmake

cmake/GetPugsGitRevision.cmake

packages/README.md

src/CMakeLists.txt

src/algebra/TinyMatrix.hpp

src/algebra/TinyVector.hpp

src/language/CMakeLists.txt

src/language/PugsParser.cpp

src/language/PugsParser.hpp

src/main.cpp

src/mesh/CMakeLists.txt

src/mesh/CellType.hpp

src/mesh/Connectivity.cpp

src/mesh/Connectivity.hpp

src/mesh/ConnectivityComputer.cpp

src/mesh/ConnectivityDescriptor.hpp