Utilise `PetscSection` to constrain essential boundary conditions #9170

Job	Run time
pytest-ubuntu-py311-gcc11-cxxnoomp-base	4m 52s
pytest-ubuntu-py312-gcc13-omp-adjoint	4m 54s
pytest-ubuntu-py310-gcc9-omp-base	4m 52s
pytest-ubuntu-py311-gcc10-noomp-adjoint	4m 52s
pytest-ubuntu-py312-gcc13-omp-base	4m 53s
pytest-ubuntu-py310-gcc14-omp-adjoint	5m 17s
pytest-ubuntu-py312-gcc12-cxxomp-adjoint	5m 17s
pytest-docker-py310-gcc-omp-adjoint	5m 16s
pytest-docker-py310-gcc-omp-arm64-base	4m 53s
pytest-docker-py310-gcc-omp-arm64-adjoint	4m 53s
pytest-ubuntu-py311-gcc10-noomp-base	4m 58s
pytest-docker-py310-icx-omp-base	4m 55s
pytest-ubuntu-py310-gcc9-omp-adjoint	4m 54s
pytest-ubuntu-py313-gcc14-omp-base	5m 16s
pytest-docker-py310-gcc-omp-base	4m 54s
pytest-ubuntu-py311-gcc11-cxxnoomp-adjoint	4m 52s
pytest-ubuntu-py312-gcc12-cxxomp-base	4m 52s
pytest-ubuntu-py313-gcc14-omp-adjoint	4m 55s
pytest-ubuntu-py310-gcc14-omp-base	4m 52s
pytest-osx-py312-clang-omp-base	4m 54s
pytest-docker-py310-icx-omp-adjoint	4m 54s
	1h 44m 15s

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