Spatial timeseries 2d representation

[Spatial timeseries](https://nwb-schema.readthedocs.io/en/latest/format.html#sec-spatialseries) represent the movement in the 2D space during time. For instance, it may represent the movement of a rat in a cage during the experiment.

With this first implementation, we want to represent all the points in a static 2D plot, ignoring the time.

- [ ] On the backend, adapt the model interpreter in order to send the data of a spatial time series. It must support lazy loading (with import value) and send axes x, y and time line.
- [ ] On the frontend, write a component that visualizes a spatial time series
- [ ] Attach the component to the code.

Examples:
- https://github.com/OpenSourceBrain/NWBShowcase/blob/master/ScholzEtAl2019/Testing.ipynb
- https://portal.nersc.gov/project/crcns/download/ssc-7/data.tar.gz

Start by tracing the backend model interpreter and the frontend integration points; the issue does not name specific files. Review the linked Spatial timeseries schema and examples, then determine how lazy loading with import values can provide x, y, and time data. Done means a frontend component renders the spatial timeseries as a static 2D plot and is attached to the application.

Written by the indexing model from the issue text.