Compatability with arrow fixed-shape-tensor extension

[jleibs]

The arrow project has an official extension for fixed-shape-tensors: https://arrow.apache.org/docs/dev/format/CanonicalExtensions.html#fixed-shape-tensor

Our current tensor APIs use a rerun-specific tensor format that stores tensor-dimension as a data field, giving us support for dynamic-shape-tensor.

Using fixed-shape-tensor ourselves would be quite a bit of work at this point with two major challenges:

1. We need a mechanism to surface metadata from components.
2. We need to be careful about how metadata is tracked and impacted by things like batching.

That said, users that are already working with arrow tensors from some other library would benefit from ergonomic support for forwarding these on into Rerun directly. This might be another interesting use-case for derived components.