Constraints:remove_cv_t<Owner> is a rebindable owner. Block models unsigned_integer, so bool and int
are turned away.
Result: The same owner over remove_cv_t<Block>, every other argument kept: the width, the key, the mapping
and the comparison. A storage changes its block through its bit_storage_rebind, which rebinds an allocator A to
allocator_traits<A>::rebind_alloc<remove_cv_t<Block>>, and recounts a count of blocks to hold the same width.
bit_rebind<uint8_t, basic_bit_array<uint64_t, 9>> is basic_bit_array<uint8_t, 9>, and
bit_rebind<uint32_t, basic_bit_fixed_set<size_t, uint8_t, 9, bit_key_mapping<size_t>, greater<size_t>>> is
basic_bit_fixed_set<size_t, uint32_t, 9, bit_key_mapping<size_t>, greater<size_t>>.
bit_rebind<uint8_t, bit_vector> is basic_bit_vector<vector<uint8_t>>, and
bit_rebind<uint16_t, bit_small_vector<9>> is
basic_bit_small_vector<uint16_t, 64, boost::container::new_allocator<uint16_t>>, the 64 bits its inline block holds.
The owner rebound holds the same bits: bit_rebind<uint8_t, bit_vector> constructed from a bit_vector's
iterators has its size and its elements, in vector<uint8_t> blocks.
bit_rebind<const volatile uint8_t, bit_vector> is bit_rebind<uint8_t, bit_vector>: a block is held by value.
Remarks: The form is that of simd's rebind_t, the new block first.