Use uv in CI and to build images

[eapolinario]

Tracking issue

flyteorg/flyte#5346

Why are the changes needed?

As described in the issue, let's adopt uv as the package installer for flytekit.

What changes were proposed in this pull request?

Use uv in a few places:

1. when setting up a dev environment via the new make target setup-uv. This assumes that a virtual environment (e.g. uv venv) is already setup prior to calling this. This keeps the tradition of not being too prescriptive about venvs.
   i. we can make this the default once we're satisfied with it. This will require a slight change to the docs.
2. the default flytekit image is now built using uv
   i. Notice the use of --system to ensure the packages are installed in the global environment.
3. the dev flyte image is also built using uv
4. We should probably also build the agent image with uv.

How was this patch tested?

Tested CI locally.
I built and used the other two images in local sandbox.

Setup process

Screenshots

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Related PRs

Docs link

[eapolinario]

This will probably break on windows.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.90%. Comparing base (d2c7ddc) to head (dd7f820).
Report is 34 commits behind head on master.

❗ Current head dd7f820 differs from pull request most recent head dd9952e. Consider uploading reports for the commit dd9952e to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2403      +/-   ##
==========================================
+ Coverage   72.27%   75.90%   +3.62%     
==========================================
  Files         181      181              
  Lines       18302    18393      +91     
  Branches     3576     3601      +25     
==========================================
+ Hits        13228    13961     +733     
+ Misses       4460     3831     -629     
+ Partials      614      601      -13     

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[eapolinario]

dbt failures are unrelated. Being tracked in flyteorg/flyte#5351.