- Added `copyRange()` to `StructureOfArrays` to efficiently copy a range
of elements from another SoA of the same type. It uses `std::copy_n`
which leverages `memcpy` for trivially copyable types.
- Added `operator[]` to `StructureOfArrays` returning `IteratorValueRef`.
- Added `operator=` for `Structure` (tuple) to `IteratorValueRef` to
allow direct assignment: `soa[i] = tuple`.
- Added unit tests for these new methods in `test_StructureOfArrays.cpp`.
