Instrument block_on about console HOT 1 CLOSED

We could either consider it a form of spawn, thus using runtime::spawn for the span and setting the kind=block_on or kind=main. Or, we could call it runtime::block_on, but then we'd need to add support to the Console to look for that new span.

hmm...in retrospect, perhaps a better name would have been runtime::task, rather than runtime::spawn. i think it's a little more reasonable to think of block_on as being a "task" than as being a "spawn". but, i dunno if it's worth the effort of renaming everything again (and adding another set of backwards compatibility names for in case people are using old tokio versions) just to make it the most correct possible.

honestly, i would probably just add a span in Tokio with the runtime::spawn name and kind=block_on...that seems like the lowest effort and doesn't require new code in the console. we could then consider renaming the target from spawn to task in a follow-up?

from console.