Arm backend: Add dim mapping helpers

Dim args such as sum(dim=1) needs to be transformed
when swapping place with operators which change
shape, i.e. permutes and views.

ViewMap and PermuteMap handles and validates these
transforms for reduction dims and permute dims.

Signed-off-by: Adrian Lundell <adrian.lundell@arm.com>
Change-Id: I634f4494df37294d4ac3397f8457bedfd20f5830

Author: AdrianLundell