[reference model] Add shape operators

- fixed up reshape conformance tests to use shape input instead of attribute
- fixed up tile conformance tests to use shape input instead of attribute
- fixed output and output rank of dim op
- allow rank 0 and rank 1 tensors for tosa.shape values (for shape = {})
- added initialization of rank 0 const_shape tensors (for shape = {})
- Update conformance tests to use new rescale attributes

Signed-off-by: Tai Ly <tai.ly@arm.com>
Signed-off-by: Won Jeon <won.jeon@arm.com>
Change-Id: I6cce0d2a9ab066fe20a2abf9d2cfde3eb3d8c18b