Document tracemalloc support and usage for debugging

[jakirkham]

The only info I could find was this note in the release. Would be nice to have some docs explaining what this is and showing how to use it.

[juliantaylor]

I'd rather deprecate the tools (so remove them from the sdist again). They are obsolete with the tracemalloc support we added a while back.

[jakirkham]

That’s unrelated.

[seberg]

This exists here now.

[jakirkham]

This exists here now.

Thanks Sebastian! 🙏

cc @stuarteberg (in case this is of interest)