Enable ruff.isort, apply fixes

contrib/c-integer-semantics.py

contrib/mem-pattern-explorer/pattern_vis.py

doc/conf.py

examples/fortran/matmul-driver.py

examples/python/call-external.py

examples/python/find-centers.py

examples/python/global_barrier_removal.py

examples/python/hello-loopy.py

examples/python/ispc-stream-harness.py

examples/python/rank-one.py

examples/python/sparse.py

examples/python/vector-types.py

loopy/__init__.py

loopy/__main__.py

loopy/auto_test.py

loopy/check.py

loopy/cli.py

loopy/codegen/__init__.py

loopy/codegen/bounds.py

loopy/codegen/control.py