Provide a "summary" view with top hotspots

[julienw]

This view comes from the hotspot tool:

┆Issue is synchronized with this Jira Task

[julienw]

I'm not sure this is useful with what we already have. But tell me what you think @mstange @gregtatum @zoepage .

[digitarald]

@julienw would this similar to heaviest stack trace? https://help.apple.com/instruments/mac/current/#/devd53abb62

[julienw]

I'm not sure what "heaviest stack trace" means.

I think this is a subset of #15, especially the first point of what Mike Conley described there.

I tried to implement this in #1538, except in this experiment I used the self time instead of the inclusive time to sort functions, but we want the inclusive time here.

The hotspot above keeps only a part of the list, kind of what I did in #1534 (360 view, aka summary view).

[digitarald]

I continued some discussion in #15 to narrow down the initial feature request.