chore: Rearrange code to support both existing and new Rust FFI based pynumaflow

[BulkBeing]

#257

The image builds were tested in an older commit without pushing images (https://github.com/numaproj/numaflow-python/actions/runs/18615039840)

The Readme.md (referenced in pyproject.toml) and LICENSE is copied to packages/pynumaflow so that they will be included in the source/wheel distribution.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.53%. Comparing base (321942d) to head (4ae1a16).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #258      +/-   ##
==========================================
- Coverage   93.63%   93.53%   -0.11%     
==========================================
  Files          65       65              
  Lines        2907     2907              
  Branches      152      152              
==========================================
- Hits         2722     2719       -3     
- Misses        135      138       +3     
  Partials       50       50              

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[vigith]

just move the Readme rather than copy?

[vigith]

for pyproject.toml, can we give relative path for the the LICENSE?

[kohlisid]

@vigith we're thinking for unified releases or seperate wheels?

[vigith]

@vigith we're thinking for unified releases or seperate wheels?

separate wheels

[BulkBeing]

for pyproject.toml, can we give relative path for the the LICENSE?

$ poetry build
Invalid entry in [project.license-files]: '../../LICENSE' ('..' must not be used.)