feat: serving and tracking endpoint for Numaflow

[vigith]

Initial code commit for the serving endpoint for Numaflow. A series of changes are required via followup PRs before we can make it production ready.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 56.93%. Comparing base (8da7c22) to head (f0b25ac).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1765 +/- ## ========================================== - Coverage 56.99% 56.93% -0.07% ========================================== Files 218 218 Lines 17581 17581 ========================================== - Hits 10021 10010 -11 - Misses 6709 6721 +12 + Partials 851 850 -1 ```

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