Onboard ci-mgmt

[rquitales]

Proposed changes

This PR revives #1474 by rebasing and modifying to fit the latest changes to pulumi-eks and ci-mgmt.

Changes made:

• Restructure the go modules to align with bridged providers for now
• Generated ci-mgmt workflows
• Added kubectl installation as a setup step
• Runs all tests in parallel across 25 shards (including upgrade tests)
• Fixed the ignore-sclaing-changes test code to be valid

Passing alpha release: https://github.com/pulumi/pulumi-eks/actions/runs/12961981890

Related issues (optional)

[github-actions]

Does the PR have any schema changes?

Looking good! No breaking changes found.
No new resources/functions.

Maintainer note: consult the runbook for dealing with any breaking changes.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 84 lines in your changes missing coverage. Please review.

Please upload report for BASE (master@5c42f19). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
provider/cmd/pulumi-gen-eks/main.go	0.00%	84 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##             master   #1596   +/-   ##
========================================
  Coverage          ?   0.00%           
========================================
  Files             ?       1           
  Lines             ?    2806           
  Branches          ?       0           
========================================
  Hits              ?       0           
  Misses            ?    2806           
  Partials          ?       0           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.