Extract tests from code in GN1

Issue:
https://github.com/genenetwork/gn-gemtext-threads/blob/main/topics/gn1-migration-to-gn2/clustering.gmi

* gn3/computations/slink.py: Add dummy `nearest' function
* tests/unit/computations/test_slink.py: Add some tests

  This commit adds tests to try and reproduce the working of the `nearest'
  function in:
  https://github.com/genenetwork/genenetwork1/blob/master/web/webqtl/heatmap/slink.py

  This commit might not yet have extracted all the expected behaviour of the
  `nearest' function, and therefore, there is a possibility of a later commit
  augmenting the work in this commit.

0 files changed, 0 insertions, 0 deletions