Allow Multimeter values to be locked by clicking links

Summary: Ref T6930. Mostly just playing with the UI a bit, I imagine we'll end up somewhere with a set of more standard query tools in the long run. But this feels pretty good/natural so far.

Test Plan:

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T6930

Differential Revision: https://secure.phabricator.com/D12628