allow dynamically updating values displayed in the "feature properties" table

**Is your feature request related to a problem? Please describe.**

In `xdggs`, I'm using a slider object to select data along different dimensions and color the rendered polygon features accordingly.

Clicking on a feature in the map opens a side panel containing additional properties of the selected feature. However, while it is possible to (ab)use the `get_fill_color` accessor of a layer to change the displayed color, the table of feature properties is static to avoid re-transmitting the feature geometries (which is costly).

**Describe the solution you'd like**

A way to dynamically update the data displayed in the side panel.

I'm absolutely not sure if this is the best way, but to do this I was thinking of creating a layer extension that registers a separate traitlet to transfer the data to the browser. When receiving data, the extension would then append / replace a column in the table.

I guess what I'm asking is whether this is possible already from an external package, or whether there'd need to be changes to either `lonboard` or `deck.gl`.

**Describe alternatives you've considered**

Disabling the "feature properties" side panel somehow, but that would be a shame because this information is definitely useful.

No file, test, or entry point is named. Start by tracing the feature-properties side panel and the layer-extension or traitlet path described in the issue, then determine whether a separate data transfer can update the table without retransmitting geometries. Done means the selected feature’s displayed properties change dynamically while its geometry remains cached.

Written by the indexing model from the issue text.