Accumulating hashes with a byte/boolean array didn't include enough
information for a useful hash, creating hashes with many collisions.
This is the root cause of a performance regression since 3.3 where
mesh data (used for storing edit-mesh undo steps) was changed to store
selection in a boolean array, creating a bottleneck de-duplicating
chunks of that array for edit-mesh undo's custom-data de-duplication.
Resolve by increasing hash accumulation for arrays with smaller elements,
so each chunk of memory (a candidate for de-duplication) isn't as likely
to have hash collisions.
`char` (single byte) arrays now accumulate 22 values instead of 7, it's
taking more values into account was necessary as these are effectively
bits in the case of boolean arrays, 2-byte values accumulate 32 bytes,
4-byte elements accumulate 44 bytes, larger structs accumulate
`sizeof(type) * 7` bytes (as before).
Also ensure the accumulation read-ahead never exceeds the chunk size -
technically a fix although this would only happen when passing a small
`chunk_count` to BLI_array_store_create (in the range of 1-16) so this
didn't happen in practice.
Improve performance of array de-duplication, see: #105046.
7a5cb3b470