customFullTimeFormat: add optional detail argument, use it in query overview

1. I added a second argument called 'detail' to customFullTimeFormat. If
   present and false, the string returned will be truncated to two time
   units -- e.g., hours and minutes, or minutes and seconds. If missing
   or true, the full detail string will be returned.

2. I added µs as one of the units of time. It's weird to have hours,
   minutes, seconds, ms, then skip straight to ns.

3. I made 'H' lowercase to match the other time unit cases.

4. I set the 'detail' argument to 'false' on the query overview tab.
   Everyone else, it's still full detail (albeit with µs).