Migrate azure pipeline environment creation from conda to mamba

[justinGilmer]

PR Summary:

Previously, all conda environment creations use conda for the dependency resolution, which is notoriously slower than mamba's implementation.

This can have a noticeable impact on run times during CI as well as building docker images. Mamba has replaced conda in our dockerfile as well as our azurepipelines.yml file.

NOTE: mamba is not used for windows builds, due to previous issues attempting to use mamba.

PR Checklist

---

• [ ] Includes appropriate unit test(s)
• [ ] Appropriate docstring(s) are added/updated
• [ ] Code is (approximately) PEP8 compliant
• [ ] Issue(s) raised/addressed?

[codecov[bot]]

Codecov Report

Merging #447 (2e79bb2) into master (f4a7f88) will not change coverage. The diff coverage is n/a.

:exclamation: Current head 2e79bb2 differs from pull request most recent head 5b951b6. Consider uploading reports for the commit 5b951b6 to get more accurate results

@@           Coverage Diff           @@
##           master     #447   +/-   ##
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  Coverage   73.84%   73.84%           
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  Files          17       17           
  Lines        1839     1839           
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  Hits         1358     1358           
  Misses        481      481