fullscreen/realtime interface for samples

[jjallaire]

This PR introduces a new fullscreen display UI that includes the traditional Inspect task view with additional panes with running samples and log/console output. Running samples have a live transcript along with the ability to cancel and score. (or cancel raising an error for evals with fail-on-error policies):

The new UI is not currently enabled by default, but we'd like people to experiment with it and provide feedback before we make it the default (in ~ 2 weeks). You can enable fullscreen mode using the --display option or the INSPECT_DISPLAY environment variable:

# enable globally in .env
INSPECT_DISPLAY=full

# enable for a single eval
inspect eval ctf.py --display full

The available values for the display option are:

• full - Fullscreen UI as shown above
• rich - Classic progress UI (currently the default)
• plain - No progress UI but print task summary at the end w/o using ANSI colors/formatting
• none - No display at all

We'll be working on several enhancements to fullscreen mode in the near future:

1. Realtime display of scores/metrics in the task view
2. Human approver will run in a new "Approval" tab and be async (so other samples/tasks keep running while approval is pending)
3. Ability to add custom panels (much like the current input_screen() but async and with richer UI constructs available via textual

[rusheb-apollo]

HUGE!