MLBEDSW-11039: Elementwise reduce axis optimisation
Moved GraphIrOptimiser function OptimiseElementwise to scheduler decompose and expanded it to squash any leading dimensions into the height. This fixes ineffective elementwise decomposition when the leading axes have large values.
Change-Id: I27c1253a4dae42ef40960ec6e47b293947a52e3d Signed-off-by: Max Bergfelt max.bergfelt@arm.com