It is impossible to specify a different arrival_time and departure_time in a GTFS-RT trip modification object

### Describe the problem

I want to specify a vehicle on a detour journey which has an extended stop at a station to make up time. It is impossible to do so in a GTFS-RT trip modification object.

### Use cases

There is a bus which runs along stops A to G. However, a roadwork has forced the bus to skip these stops, so it has to run on a more direct route with an interchange at X. The bus will have an extended layover at X such that it will run on the original static time in the unaffected section, and to allow as many passengers as possible to change there for alternative journeys.

### Proposed solution

To allow specifying both arrival and departure times in trip_modifications

### Additional information

_No response_