2D view is clipping some data on the edges

[teh-cmc]

Consider this:

• The top and bottom edges of e.g. the green rectangles are missing half their stroke width because the 2D view size doesn't take the radius into account
• The right edge gets the same treatment, and in addition to that gets clipped some more because of the vertical separator of the selection panel

Worse, we're clipping an entire label here, as can be seen by moving one of the rectangle around:

[jleibs]

Note: fixing the rectangle edges probably isn't that bad here, but capturing the labels inside the bounding box will be more involved.

The challenge is that bounding boxes are updated from the SceneSpatialPrimitives https://github.com/rerun-io/rerun/blob/jleibs/delete_classic_tensor/crates/re_viewer/src/ui/view_spatial/scene/primitives.rs#L66 but that structure doesn't have access to the labels.

[Wumpf]

Actually, the labels are placed by create_labels which is unified as of #1438 - that method could easily take the bounds into consideration and decide when a label should be snapped inside

[emilk]

We could solve the labels by moving them to inside of the visible viewport when painting them