Add goal inference and time series projects

[jpchen]

Motivation

Since there are fewer BM maintainers within Meta, I wanted to open source intern infra projects (by James and Zhen) built on BM for external research and future use. These are all implementations of publicly available papers and contain no internal data. I would like to get this in if tests pass and defer design and functionality questions to a future PR since these things are a bit time sensitive.

Test Plan

I've run this internally, but I'm having issues installing BM on my laptop now (I'll open a separate issue about that) so I'm going to defer to CI's testing. Note that the individual tests for the two experimental projects are not being run as part of our CI suite but since they are experimental, that is not a blocker atm.