Extend the Performance Bar with a button to see memory profile

Problem to solve

As proposed in https://gitlab.com/gitlab-org/gitlab-ce/issues/62270#future-extensions, extend Performance Bar to provide information about memory allocation and sources of allocations.

Intended users

Sasha (Software Developer)

Devon (DevOps Engineer)

Proposal

Currently there is a profile button to do line-profiling. We can add another button memory to invoke memory profiling.

To make the wording more natural, we can rename profile to lineprof. (however we may keep it as profile today, since there is a proposal https://gitlab.com/gitlab-org/gitlab-ce/issues/62270#note_193793549 to replace line profiling to call-stack profiling using stackprof. it will be another story).

What does success look like, and how can we measure that?

Being able to show memory profile of the Gitlab.com page via performance bar.

Links / references

https://docs.gitlab.com/ee/administration/monitoring/performance/performance_bar.html