Fix soundness gaps in date parsing

In working on some metrics queries in the browser, I found that processResponseBody failed to capture and transform the startTimes and timestamps iso string arrays into values of type Date[], so they were quietly wandering around as string arrays instead. This was already a theoretical issue in console, but papered over by passing the timestamps into a Date constructor (redundant but allowable from typescript's perspective, and made the strings into actual dates at runtime).

Pretty simple explanation: the parseIfDate utility is only configured to capture ISO strings, not arrays of them! That's true in both its key inspection (which concerns itself with "time" and not "times"), and its value inspection. While here, I was also curious if the "has the word time somewhere" heuristic was complete enough, which it isn't: created, first_seen and last_seen are meant to be Date, but also missed.