Plugins for flyteadmin server middleware (try2)

[katrogan]

TL;DR

Enables flexibility in flyteadmin serving, such as custom authentication/audit logging middleware, authorization hooks and more

This second attempt makes sure to register the default before fetching the plugin

Tested this on flyte deployment with auth enabled and verified the authorization interceptor was running

Type

• Bug Fix
• Feature
• Plugin

Are all requirements met?

• Code completed
• Smoke tested
• Unit tests added
• Code documentation added
• Any pending items have an associated Issue

Complete description

How did you fix the bug, make the feature etc. Link to any design docs etc

Tracking Issue

fixes flyteorg/flyte#2507

Follow-up issue

NA

[codecov]

Codecov Report

Merging #428 (4fccab5) into master (ede2297) will increase coverage by 0.12%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #428      +/-   ##
==========================================
+ Coverage   61.21%   61.33%   +0.12%     
==========================================
  Files         155      156       +1     
  Lines       11088    11095       +7     
==========================================
+ Hits         6787     6805      +18     
+ Misses       3597     3586      -11     
  Partials      704      704              

Flag	Coverage Δ
unittests	60.25% <100.00%> (+0.10%)	⬆️

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

Impacted Files	Coverage Δ
plugins/registry.go	100.00% <ø> (ø)
auth/interceptor.go	100.00% <100.00%> (ø)
auth/identity_context.go	29.72% <0.00%> (+29.72%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ede2297...4fccab5. Read the comment docs.