add support for mlflow in caliban shell

[ajslone]

This PR adds support for mlflow reporting via cloud_sql_proxy in caliban shell.

[codecov[bot]]

Codecov Report

Merging #83 into master will increase coverage by 0.07%. The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master      #83      +/-   ##
==========================================
+ Coverage   51.83%   51.90%   +0.07%     
==========================================
  Files          31       31              
  Lines        3158     3169      +11     
==========================================
+ Hits         1637     1645       +8     
- Misses       1521     1524       +3     

Impacted Files	Coverage Δ
caliban/platform/run.py	27.96% <0.00%> (-0.49%)	:arrow_down:
caliban/docker/build.py	33.78% <25.00%> (-0.01%)	:arrow_down:
caliban/platform/shell.py	35.48% <50.00%> (+1.00%)	:arrow_up:
caliban/util/metrics.py	100.00% <100.00%> (ø)
caliban/platform/gke/util.py	71.37% <0.00%> (+0.38%)	:arrow_up:
caliban/platform/cloud/types.py	90.50% <0.00%> (+0.63%)	:arrow_up:

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