Allow to replace long links via API

[forki]

The API doesn't allow to replace long links that are shortened with custom ending.

Expected Behavior

If we send a shorten acttion we'd link to replace old (i.e. broken) links that are available under a custom ending.

Current Behavior

No solution available. At least we did not find anything in the docs.

Context

We'd like to keep stable shortlinks for potentially changing long links.

[ngsoftDE]

There is no implementation yet