feat: generator based on ticker

[vigith]

fixes: #2125

[codecov]

Codecov Report

Attention: Patch coverage is 96.78899% with 7 lines in your changes missing coverage. Please review.

Project coverage is 53.37%. Comparing base (06515a2) to head (90c791c).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
rust/numaflow-core/src/source/generator.rs	96.69%	7 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2126       +/-   ##
===========================================
- Coverage   64.02%   53.37%   -10.66%     
===========================================
  Files         325      327        +2     
  Lines       31239    37748     +6509     
===========================================
+ Hits        20002    20148      +146     
- Misses      10195    16558     +6363     
  Partials     1042     1042               

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[yhl25]

LagReader should be cloneable.