Call tree width needs to take into account the size of items

See this screenshot, shared by staktrace in [bug 1633455](https://bugzilla.mozilla.org/show_bug.cgi?id=1633455):

Currently our call tree width is computed using an heuristic that takes into account only the call tree's depth but not the call tree's items:
https://github.com/firefox-devtools/profiler/blob/8a76c7490bd03ef737c0affdaeb8dabe63149ec7/src/components/shared/TreeView.js#L727
I believe it stays fixed for performance reasons (?).

Not sure what the right path is here. I wonder what the missing part is: is it only arguments? or can it be the function name if the return type has a lot of templating? Should we remove some of this templating instead, like keeping only the outer object (but in the case of Rust types, we would keep sometimes Box/Arc which isn't meaningful)? Or shorten each part? Lots of questions :-)

stacktrace do you think you can share with us a link to this profile? Thanks!

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-255)