Implement a unified / interleaved view of multiple profiles

We have profile diffing as an idea, but here I'm referring to the opposite. Essentially, interleaving the samples from two or more profiles (attempting to match process by process) to create a super-profile.

The use case here is for analyzing talos profiles. I.e., profiles of very similar runs which should roughly line up, allowing us to virtually increase the sampling rate without actually incurring extra overhead. This would be particularly useful for diffing N talos runs with N other talos runs when the percentage performance difference is low but consistent.

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-212)