Homestyx hydra

R1:a0a346be347e

In Herald transcripts, render some field values in a more readable way

Summary:
Ref T13480. Currently, some Herald field types are rendered in an unfriendly way on transcripts. Particularly, PHID lists are rendered as raw PHIDs.

Improve this by delegating rendering to Value objects and letting "PHID List" value objects render more sensible handle lists. Also improve "bool" fields a bit and make more fields render an explicit "None" / empty value rather than just rendering nothing.

Test Plan: Viewed…
Repository: R1 hydra
Commit Date: Jan 29 2020