Add a design document proposal to support open in VU context

[oleiade]

This draft aims to address #3020, focusing on enabling k6 scripts to access files directly from the VU stage, not just the init stage.

While the primary focus is on file access, I've currently left out considerations regarding require from #3020. If require should be part of this discussion, based on similar requirements or challenges, I'm more than open to updating the proposal to encompass it.

If you've got alternative solutions or insights, please contribute with a separate commit.

I'm eager to hear your thoughts and feedback in the comments below. Thanks for taking the time to review! 🙇🏻

[codecov-commenter]

Codecov Report

All modified lines are covered by tests :white_check_mark:

Comparison is base (6fa8abd) 72.96% compared to head (1e7aba0) 72.96%.

:exclamation: Current head 1e7aba0 differs from pull request most recent head f708952. Consider uploading reports for the commit f708952 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3358   +/-   ##
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  Coverage   72.96%   72.96%           
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  Files         261      261           
  Lines       20018    20018           
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  Hits        14607    14607           
  Misses       4484     4484           
  Partials      927      927           

Flag	Coverage Δ
ubuntu	72.90% <ø> (-0.01%)	:arrow_down:
windows	72.82% <ø> (+0.01%)	:arrow_up:

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[oleiade]

Heads-up that @codebien volunteered himself to take over this topic, and will be handling the discussions and work on that front from now on 🙇🏻

PS: @szkiba expressed interest in proposing an alternative solution for this too 👍🏻