Ability to filter by category / subcategory

This issue is the modern successor of #102.

The categories in the sidebar give a good overview of what's going on in a profile, but they don't allow you to drill down. I'm missing the following functionality:

* The ability to filter samples to only show samples of a selected category.
* The same for a subcategory.
* The inverse: the ability to _hide_ any samples from a given category, for example Idle samples.

I think such a category filter could be added to the filtering pipeline in a similar way as the search filter: It can be independent from the transform stack and the time range filter stack. It only filters samples, it does not affect the shape of the call tree.

I'm undecided whether this filter should be stick around as you select different threads, the way the search filter does.

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-175)