frontend: Create missions (surveys) where the sensor only exist in one side of the vehicle

### Current behaviour

Different from an aerial camera where the overlap and position of the captured data is centralized with the vehicle body. A sidescan sample only exist on the side of the vehicle.
With the current survey configuration, using blueboat with a sidescan results in missions with holes.


### Expected or desired behaviour

We should have a survey configuration where we can scan with the sidescan without holes. Maybe having a ratio between lines, where a ratio of 2:0 would fix the issue.


### Prerequisites

- [x] I have checked to make sure that a similar request has not already been filed or fixed.

Start by locating the frontend survey-configuration entry point and the code that handles sidescan missions for BlueBoat. Compare the current line-planning behavior with the attached examples and determine how a side-specific ratio should be represented. Done means sidescan surveys can be configured without coverage holes and the resulting mission matches the intended layout.

Written by the indexing model from the issue text.