Capturing piplite install messages

### References

- follow-on to jupyterlite/jupyterlite#469
- would have helped find some URL issues over on jupyterlite/jupyterlite#472, jupyterlite/jupyterlite#474

### Problem

The various `piplite` messages are very chatty in the console log when everything is working fine, and still rather hidden when something fails. Kernel-level (as opposed to client-level) issues should probably be caught and made more explicitly discoverable to users.

### Proposed Solution

Capture more pyodide startup messages into the in-UI log handler.

### Additional context

- The `loadPackage` function accepts some message handlers
- we should use the kernel logging system for this
- disabling `fullStdLib` would let us more finely tune the initial imports
- `loadPackage` is also called by [micropip](https://github.com/pyodide/pyodide/blob/main/packages/micropip/src/micropip/_micropip.py#L203)
- we can also patch that in `piplite` to use our handlers
- during UI tests, we should keep this open and start ensuring there are no "unexpected" messages... might be an interesting challenge...