🌱 add license checker in workflow

[jasonliu747]

Ⅰ. Describe what this PR does

This PR will check whether the license headers are included in the source code files. So reviewer won't need to verify it one by one. CI will fail if the license header is missing.

Ⅳ. Special notes for reviews

Blocked by #116

[codecov-commenter]

Codecov Report

Merging #117 (5d64391) into main (73eb08c) will increase coverage by 10.15%.
The diff coverage is 72.11%.

❗ Current head 5d64391 differs from pull request most recent head 9845132. Consider uploading reports for the commit 9845132 to get more accurate results

@@             Coverage Diff             @@
##             main     #117       +/-   ##
===========================================
+ Coverage   44.19%   54.34%   +10.15%     
===========================================
  Files          73       77        +4     
  Lines        5965     7277     +1312     
===========================================
+ Hits         2636     3955     +1319     
+ Misses       3036     2972       -64     
- Partials      293      350       +57     

Flag	Coverage Δ
unittests	54.34% <72.11%> (+10.15%)	⬆️

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

Impacted Files	Coverage Δ
pkg/koordlet/audit/auditor.go	72.57% <ø> (ø)
pkg/koordlet/audit/config.go	73.33% <ø> (ø)
pkg/koordlet/audit/event_logger.go	69.51% <ø> (ø)
pkg/koordlet/audit/logger.go	72.30% <ø> (ø)
pkg/koordlet/audit/types.go	35.48% <ø> (ø)
pkg/koordlet/config/config.go	69.23% <ø> (ø)
pkg/koordlet/metriccache/config.go	0.00% <ø> (ø)
pkg/koordlet/metriccache/fake_metric_cache.go	0.00% <ø> (ø)
pkg/koordlet/metriccache/metric_cache.go	45.88% <ø> (ø)
pkg/koordlet/metriccache/storage.go	92.40% <ø> (ø)
... and 72 more

---

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[hormes]

/lgtm
/approve

[koordinator-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hormes

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