Do not use global types as a template type names

- The shape_t and tensor_list_t types are defined globally and cannot be used as
template type names.
- Neither CUSTOM nor CONST_SHAPE require a template type be used and a single
type support entry without a template type can be used.
- Also use monospace font for type names in section that defines shape_t and
tensor_size_t.

Change-Id: Ida88451d167fedf966894f3b5b5f2945f7633860
Signed-off-by: Kevin Petit <kevin.petit@arm.com>