ENH: Don't add a metadata instance with only one object

[ZLLentz]

Description

• If any of the metadata namespaces has one or fewer objects contained, don't bring them to the ipython session.
• add utility function for counting the metadata namespaces

Motivation and Context

Without this fix, anything in the user's beamline file with an underscore becomes a metadata namespace!

For example, safe_load gets repackaged as safe.load, which is undesirable.

closes #78

How Has This Been Tested?

• added test for the utility function
• add check for tst object that I broke, to make sure I didn't break it
• verified in tstpython

Where Has This Been Documented?

Added to the utils api docs

[codecov-io]

Codecov Report

Merging #85 into master will increase coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #85      +/-   ##
==========================================
+ Coverage   98.72%   98.74%   +0.02%     
==========================================
  Files          14       14              
  Lines         548      557       +9     
==========================================
+ Hits          541      550       +9     
  Misses          7        7

Impacted Files	Coverage Δ
hutch_python/utils.py	97.93% <100%> (+0.16%)	⬆️
hutch_python/load_conf.py	98.48% <100%> (+0.02%)	⬆️

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