Add NodeMetadata.Config property bag and expose ClusterAssignment in LaunchPlan

[EngHabu]

Why are the changes needed?

This allows plugins to pass execution instructions to the backend plugin without having to introduce new protos..

What changes were proposed in this pull request?

Allow passing cluster_assignment in Workflow NodeMetadata and LaunchPlan.

How was this patch tested?

Deployed to an internal tenant and verified the bits are passed correctly.

Setup process

Screenshots

Check all the applicable boxes

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

Summary by Bito

This PR introduces a new config property bag in NodeMetadata enabling plugins to pass execution instructions without new proto definitions, and adds support for cluster_assignment in LaunchPlan specifications. The changes span across multiple language implementations including Go, TypeScript, Python, and Rust, enhancing the flexibility of plugin configuration and execution control.

Unit tests added: False

Estimated effort to review (1-5, lower is better): 5

[flyte-bot]

Code Review Agent Run Status

• Limitations and other issues: ❌ Failure - The AI Code Review Agent skipped reviewing this change because it is configured to exclude certain pull requests based on the source/target branch or the pull request status. You can change the settings here, or contact the agent instance creator at eduardo@union.ai.

[codecov]

Codecov Report

Attention: Patch coverage is 16.66667% with 10 lines in your changes missing coverage. Please review.

Project coverage is 33.25%. Comparing base (e0833b7) to head (bf93770).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...lyteidl/gen/pb-go/flyteidl/admin/launch_plan.pb.go	16.66%	5 Missing ⚠️
flyteidl/gen/pb-go/flyteidl/core/workflow.pb.go	16.66%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6173      +/-   ##
==========================================
- Coverage   37.05%   33.25%   -3.81%     
==========================================
  Files        1318     1020     -298     
  Lines      132627   108679   -23948     
==========================================
- Hits        49151    36138   -13013     
+ Misses      79226    69344    -9882     
+ Partials     4250     3197    -1053     

Flag	Coverage Δ
unittests-datacatalog	51.58% <ø> (ø)
unittests-flyteadmin	?
unittests-flytecopilot	30.99% <ø> (ø)
unittests-flytectl	62.29% <ø> (ø)
unittests-flyteidl	7.23% <16.66%> (+<0.01%)	⬆️
unittests-flyteplugins	53.85% <ø> (ø)
unittests-flytepropeller	42.69% <ø> (ø)
unittests-flytestdlib	55.27% <ø> (-0.02%)	⬇️

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