[Monorepo] Enable proxy-authorization in admin client

[eapolinario]

Describe your changes

This PR imports flyteorg/flyteidl#437 into the monorepo.

Original description

Part of an effort to integrate Flyte with GCP Identity Aware Proxy, see #3965.

Allows the flyteidl admin client to sent a "proxy-authorization" header with every request to flyteadmin. Tokens for this header are created using an external command which is configured via the new proxyCommand config entry.

Same logic as was introduced in flytekit in flyteorg/flytekit#1787.

I replicated the existing logic in MaterializeCredentials and NewAuthInterceptor for the second token. The external command is called a single time per flytectl call.

Tracking Issue

Closes #3965

Check all the applicable boxes

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

Screenshots

Note to reviewers

[codecov]

Codecov Report

Attention: 18 lines in your changes are missing coverage. Please review.

Comparison is base (4a780c3) 59.45% compared to head (85a819a) 59.94%.
Report is 4 commits behind head on master.

❗ Current head 85a819a differs from pull request most recent head d2013e9. Consider uploading reports for the commit d2013e9 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4189      +/-   ##
==========================================
+ Coverage   59.45%   59.94%   +0.49%     
==========================================
  Files         638      569      -69     
  Lines       54134    41049   -13085     
==========================================
- Hits        32183    24607    -7576     
+ Misses      19404    14053    -5351     
+ Partials     2547     2389     -158     

Flag	Coverage Δ
unittests	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
flyteidl/clients/go/admin/config.go	50.00% <ø> (ø)
flyteidl/clients/go/admin/config_flags.go	62.00% <100.00%> (+0.77%)	⬆️
...eidl/clients/go/admin/pkce/handle_app_call_back.go	94.11% <100.00%> (+0.17%)	⬆️
...lyteplugins/go/tasks/pluginmachinery/core/phase.go	21.50% <ø> (-1.27%)	⬇️
...yteplugins/go/tasks/plugins/webapi/agent/plugin.go	71.82% <100.00%> (+5.92%)	⬆️
...dl/clients/go/admin/pkce/auth_flow_orchestrator.go	51.02% <75.00%> (-12.03%)	⬇️
flytepropeller/pkg/controller/controller.go	11.56% <0.00%> (-0.19%)	⬇️
flyteidl/clients/go/admin/client.go	84.68% <70.00%> (-2.24%)	⬇️
flyteidl/clients/go/admin/auth_interceptor.go	73.75% <71.73%> (+2.32%)	⬆️

... and 555 files with indirect coverage changes

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

[eapolinario]

@fg91 , can you fix the error in single-binary propeller? It repros locally, just run make compile from the root of the repo.