Signature::vectorizes_over_list not useful at runtime only relevant to test.

[sholderbach]

When defining the input and output types #6796 already added the capability to declare that a command operates on a single scalar of a type AND a whole list/vector of this type. This can be indicated by the Signature::vectorizes_over_list method and field. But this only affects the rough testing done for the Examples. Here this field is checked to see if the Examples are member of the set of declared input_output_types.

The runtime type checker that is much more effective since #9680 does not take this into account at all. Thus several commands that support both scalar as well as list/stream values currently need to be updated in their type signature (see for example #9683)

Either we support the vectorizes_over_list field in the type check as well or we remove it and update all necessary signatures manually.

[fdncred]

I think I'd vote to remove it as I'd rather have the supported types listed in input_output_types(), otherwise some types will be hidden and less obvious.