feat: Add pprof profiling support

[sreis]

What this PR does / why we need it:

Adds pprof profiling support and accompanying documentation.

The data provided by pprof is useful to track down any potential performance bottlenecks as well to figure out areas of improvement. Being able to get a stacktrace of kubefed is also very useful.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

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[sreis]

/assign @xunpan

[jimmidyson]

Thank you @sreis!

/approve

[pmorie]

/lgtm

[jimmidyson]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jimmidyson, sreis

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