[TypeScript] Fix Field components types doesn't expose defaultProps & propTypes

[fzaninotto]

Problem

Run the demo with make demo in the latest master. The TS compilation fails with a weird

Failed to compile.

~/react-admin/examples/demo/src/visitors/ColoredNumberField.tsx
TypeScript error in ~/react-admin/examples/demo/src/visitors/ColoredNumberField.tsx(15,47):
Property 'defaultProps' does not exist on type 'NamedExoticComponent'. TS2339

   14 | 
   15 | ColoredNumberField.defaultProps = NumberField.defaultProps;
      |                                               ^
   16 | 
   17 | export default ColoredNumberField;
   18 |

Solution

Partially reverts #6538 and come back to FC. Although it has the drawback of adding an implicit children prop even when it's not necessary, it's better than typing Fields with NamedExoticComponent.