cmd/trace/v2: add thread-oriented mode for v2 traces
This is a nice-to-have that's now straightforward to do with the new
trace format. This change adds a new query variable passed to the
/trace endpoint called "view," which indicates the type of view to
use. It is orthogonal with task-related views.
Unfortunately a goroutine-based view isn't included because it's too
likely to cause the browser tab to crash.
For #60773.
For #63960.
Change-Id: Ifbcb8f2d58ffd425819bdb09c586819cb786478d
Reviewed-on: https://go-review.googlesource.com/c/go/+/543695
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Michael Pratt <mpratt@google.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>