feat(session): Adds session class to python

[rchowell]

This PR adds the daft-session to the python APIs. It is an incremental step towards merging our session/catalog/table APIs. For a more complete picture of this class and its purpose, please see the full implementation at https://github.com/Eventual-Inc/Daft/blob/b29330ae0c22e325292599d75f6749175f2f12d1/daft/session.py

[codspeed-hq]

CodSpeed Performance Report

Merging #3809 will degrade performances by 39.53%

_{Comparing rchowell/session (400dc36) with main (f9a4b70)}

Summary

⚡ 1 improvements
❌ 1 regressions
✅ 25 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	test_count[1 Small File]	3.9 ms	3.3 ms	+19.77%
❌	test_iter_rows_first_row[100 Small Files]	195 ms	322.6 ms	-39.53%

[codecov]

Codecov Report

Attention: Patch coverage is 86.95652% with 6 lines in your changes missing coverage. Please review.

Project coverage is 77.86%. Comparing base (f9a4b70) to head (400dc36).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
daft/session.py	82.14%	5 Missing ⚠️
daft/__init__.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3809      +/-   ##
==========================================
+ Coverage   75.60%   77.86%   +2.25%     
==========================================
  Files         748      750       +2     
  Lines       99035    94774    -4261     
==========================================
- Hits        74875    73793    -1082     
+ Misses      24160    20981    -3179     

Files with missing lines	Coverage Δ
src/daft-session/src/python.rs	100.00% <100.00%> (ø)
src/lib.rs	96.20% <100.00%> (+0.04%)	⬆️
daft/__init__.py	23.07% <0.00%> (-0.61%)	⬇️
daft/session.py	82.14% <82.14%> (ø)

... and 34 files with indirect coverage changes