fix(oss): Get integration tests running

Summary:
Recent changes to EdenFS have caused the OSS build of integration tests to go stale.  These are some targeted fixes to get them working again:

1. Make the python-psutil package available
2. Fix the build "egg" generation

The second one puts a wrap on all the changes required by recent updates to EdenFS that required hybrid (python+native and/or cython) libraries.

The weirdest part that was required was renaming the targets to end in `.egg` -- this is actually required by one part of the python build infrastructure which tries to detect whether it is in a directory that ends with the `.egg` extension.

Tested through building Sapling/EdenFS (requires other fixes to run clean):
```
act --container-architecture linux/x86_64 -W .github/workflows/edenfs_linux.yml
```

X-link: facebook/sapling#1133

Reviewed By: genevievehelsel

Differential Revision: D83085685

Pulled By: bherila

fbshipit-source-id: a4dfa326d4282a58ab539695bb566a275c6d6b90

Author: ben--

build/fbcode_builder/manifests/eden

@@ -27,6 +27,7 @@ rocksdb
 re2
 libgit2
 pexpect
+python-psutil
 python-toml
 python-filelock
 edencommon

build/fbcode_builder/manifests/python-psutil

@@ -0,0 +1,10 @@
+[manifest]
+name = python-psutil
+
+[download]
+url = https://files.pythonhosted.org/packages/bf/b9/b0eb3f3cbcb734d930fdf839431606844a825b23eaf9a6ab371edac8162c/psutil-7.0.0-cp36-abi3-manylinux_2_12_x86_64.manylinux2010_x86_64.manylinux_2_17_x86_64.manylinux2014_x86_64.whl
+sha256 = 4b1388a4f6875d7e2aff5c4ca1cc16c545ed41dd8bb596cefea80111db353a34
+
+[build]
+builder = python-wheel
+