added node index to current_context

[Atharva1723]

Tracking issue

Closes flyteorg/flyte#5534

Why are the changes needed?

In Flyte, when working with map tasks, outputs often risk being overwritten if they share the same static name. For example, if multiple nodes generate output files with the same name, only the last file would remain, as previous ones would be overwritten. By adding the array node index, it becomes possible to uniquely name these outputs, avoiding conflicts.

What changes were proposed in this pull request?

The key goal of this PR is to include the index of an array node in map_tasks within the current_context() returned value. This feature is especially useful when multiple nodes within a map task could potentially overwrite outputs

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[pingsutw]

mind adding a small unit test in this file?
https://github.com/flyteorg/flytekit/blob/f394bc95b94798e856649a2b07e2d87528ebd2cb/tests/flytekit/unit/bin/test_python_entrypoint.py#L342-L341

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 53.11%. Comparing base (ac7b7e8) to head (ad31d7e).
Report is 1 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (ac7b7e8) and HEAD (ad31d7e). Click for more details.

HEAD has 9 uploads less than BASE

Flag	BASE (ac7b7e8)	HEAD (ad31d7e)
	18	9

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #2812       +/-   ##
===========================================
- Coverage   81.34%   53.11%   -28.24%     
===========================================
  Files         196      226       +30     
  Lines       20324    21818     +1494     
  Branches     2619     2613        -6     
===========================================
- Hits        16533    11588     -4945     
- Misses       3063     9704     +6641     
+ Partials      728      526      -202     

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[pingsutw]

Could you run make fmt locally to fix the lint error?

[Atharva1723]

Will write an unit test and will run formatter too