Replace PsArrayAccess by PsBufferAcc

src/pystencils/backend/ast/analysis.py

src/pystencils/backend/ast/expressions.py

src/pystencils/backend/ast/util.py

src/pystencils/backend/emission.py

src/pystencils/backend/kernelcreation/freeze.py

src/pystencils/backend/kernelcreation/typification.py

src/pystencils/backend/memory.py

src/pystencils/backend/platforms/cuda.py

src/pystencils/backend/platforms/generic_cpu.py

src/pystencils/backend/platforms/sycl.py

src/pystencils/backend/platforms/x86.py

...encils/backend/transformations/erase_anonymous_structs.py

...ils/backend/transformations/hoist_loop_invariant_decls.py

src/pystencils/backend/transformations/select_intrinsics.py

tests/nbackend/kernelcreation/test_freeze.py

tests/nbackend/test_ast.py

tests/nbackend/test_cpujit.py