refactor(rust): Share source token between all sender tasks of source nodes in new-streaming engine

[orlp]

This ensures a stop request is propagated to all tasks as soon as possible.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.

Project coverage is 79.83%. Comparing base (40f8f5d) to head (1972eac).
Report is 12 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/polars-stream/src/nodes/in_memory_source.rs	0.00%	2 Missing ⚠️
...ates/polars-stream/src/nodes/parquet_source/mod.rs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #19593      +/-   ##
==========================================
- Coverage   79.83%   79.83%   -0.01%     
==========================================
  Files        1536     1536              
  Lines      211354   211357       +3     
  Branches     2445     2445              
==========================================
- Hits       168745   168744       -1     
- Misses      42054    42058       +4     
  Partials      555      555              

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