The main motivation for this change is API ergonomics: most operations
on dynarrays are really on elements, not on bytes, so it's weird to have
grow and resize as the odd operations out.

The secondary motivation is memory safety. Users of the old byte-oriented
functions would often multiply a number of elements with the element size,
which could overflow, and checking for overflow is tedious.

With this change, we only need to implement the overflow checks once.
The checks are cheap: since eltsize is a compile-time constant and the
functions should be inlined, they only add a single comparison and an
unlikely branch.

v2:
- ensure operations are no-op when allocation fails
- in util_dynarray_clone, call resize_bytes with a compile-time constant element size

v3:
- fix iris, lima, panfrost

Reviewed-by: Marek Olšák <marek.olsak@amd.com>