move cli to src/rail/cli/rail

[eacharles]

Problem & Solution Description (including issue #)

Code Quality

• My code follows the code style of this project
• I have written unit tests or justified all instances of #pragma: no cover; in the case of a bugfix, a new test that breaks as a result of the bug has been added
• My code contains relevant comments and necessary documentation for future maintainers; the change is reflected in applicable demos/tutorials (with output cleared!) and added/updated docstrings use the NumPy docstring format
• Any breaking changes, described above, are accompanied by backwards compatibility and deprecation warnings

[eacharles]

This will not result in any changes in how the cli commands re invoked, but will follow more standard practice and allow people to do python -m rail.cli.rail to invoke the cli

#171

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.36%. Comparing base (454c32e) to head (5baafeb).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #171   +/-   ##
=======================================
  Coverage   98.36%   98.36%           
=======================================
  Files          45       45           
  Lines        2502     2502           
=======================================
  Hits         2461     2461           
  Misses         41       41           

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[hangqianjun]

Looks good to me!