Add pylibefp python bindings to upstream libefp

[loriab]

Hi @slipchenko, this PR is in reasonable shape now. Sorry for the delay -- our VPN went down, so I diverted to another project for a while. I'm glad to answer any questions about the changes. Please "merge" rather than "squash and merge" this one so that the commit that copies over all the code from my repo is preserved for easier diff in case we ever need it.

I do have some other edits locally for some new capabilities, but I'm guessing Suranjan's set is more complete.

• copy pylibefp over from https://github.com/loriab/pylibefp at b3da48f ~v0.6.2
• imrprove the fraglib searching in pylibefp so _L means only from the library but w/o suffix means search along paths, including library. this gets rid of those psi4 specializations of flattening the library and turning off _L, so it can use an ordinary compile. also, use python pathlib module rather than the extra fns copied in from psi4
• pull version for cmake from libefp header
• modernize the cmake buildsys. this is imcomplete for exporting the project but is in sufficient working order for building and testing.
• to build the python bindings, one can either -D LIBEFP_ENABLE_PYTHON=ON when configuring the libefp build. or, build the python/ directory later and pass -D libefp_DIR=/path/to/libefpConfig.
• removed the include/efp.h that was probably checked in by mistake
• added qm/efp testing to GHA with psi4 for integrals

todo

• better exporting of pylibefp project
• there's lots of "LIBEFP: cannot find "nh3" in any of .efp files" that are alarming but are a conswquence of normal search. suppress these.
• redo the licensing on libefp so the project doesn't look like mixed license
• a couple of the pytest files aren't gettting installed b/c they're failing due to the new options and capabilities. review these after Suranjan's updates.

[loriab]

@slipchenko, this is ready for review. there's a few notes above.

[slipchenko]

Thanks, @loriab ! It's a lot of updates!
I will let Suranjan know that he can work against the master branch now.