[mlir][ArmSME] Add arith-to-arm-sme conversion pass (#78197)

Existing 'arith::ConstantOp' conversion and tests are moved from
VectorToArmSME. There's currently only a single op that's converted at
the moment, but this will grow in the future as things like in-tile add
are implemented. Also, 'createLoopOverTileSlices' is moved to ArmSME
utils since it's relevant for both conversions.