Removing __init__.py that prevents other estimators from being found

[OliviaLynn]

Change Description

Made this to address #11 - this problem showed up for a new user today, and I was able to reproduce this on my local machine this time around.

Solution Description

• Removed rail/creation/engine/init.py as described in the issue.
• Patched some import issues this created in the tests
• Also ran isort on the imports at the top of the tests

Note: I was unable to get the notebook running before this change (or when switching back to main branch), as the cell with pipe.initialize throws a ValueError.

When I run the notebook with this code in this PR, I can at least get to the same cell, but I can't fully check that the notebook still works as expected. I don't expect it to be affected, but I wanted to note I can't check to be sure.

Code Quality

• I have read the Contribution Guide
• My code follows the code style of this project
• My code builds (or compiles) cleanly without any errors or warnings
• My code contains relevant comments and necessary documentation

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (d9db37d) 98.39% compared to head (578a733) 98.37%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #14      +/-   ##
==========================================
- Coverage   98.39%   98.37%   -0.02%     
==========================================
  Files           3        2       -1     
  Lines         187      185       -2     
  Branches       18       18              
==========================================
- Hits          184      182       -2     
  Partials        3        3              

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