Show "brimcap info" summary within Brim

[philrz]

https://github.com/brimsec/zq/pull/1354 was the origin of pcap info as a debug/informational tool, and https://github.com/brimdata/brimcap/issues/263 notes that this is now available via brimcap info. Now that the info is available, we'd want to come up with a way in the Brim app for the user to request/view the info.

Perhaps this could be provided as a tooltip or pop-up attached to the proposed "pcap path" info described in #1042.

[jameskerr]

Great, I think that makes sense.