Feature: manual entry of time range

I have a pair of profiles of the same benchmark, and I'm trying to figure out why one is slower than the other.

I've found it useful to double-click a DOM "FirstContentfulPaint" marker on each and zoom into that time range. But then one is scaled relative to the other, and it's harder to match things up to see what is the "same" (same event, similar duration).

So if profile 1 takes 80ms in FirstContentfulPaint, and profile 2 takes 120ms, then I want to either show the first 80ms of both, or the first 120ms of both. (Usually the former.) Currently, I am manually editing the `range=200m120` portion of the URL. It works, but I had to read the code to figure out what the syntax is, and it feels a bit clunky because it's a reload (including reopening the ZIP file the profiles are stored in.)

Note that I'll do this in two adjacent tabs and flip back and forth between them to "visually diff" the profiles. It works pretty well for the most part.

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-380)