[serialization_lib] Add TosaShape to schema

This adds TosaShape to tosa flatbuffer schema, to serialize
values of tosa.shape type
and add "shapes" to the TosaBasicBlock to hold an array of
these tosa shapes.

Signed-off-by: Tai Ly <tai.ly@arm.com>
Change-Id: Ia84c7f90428d6cfe45b271ea380ee14f4a8a677a