Add license headers

[Thevakumar-Luheerathan]

Purpose

Describe the problems, issues, or needs driving this feature/fix and include links to related issues.

Fixes #44308

Approach

Describe how you are implementing the solutions along with the design details.

Samples

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Remarks

List any other known issues, related PRs, TODO items, or any other notes related to the PR.

Check List

• Read the Contributing Guide
• Updated Change Log
• Checked Tooling Support (#)
• Added necessary tests
  • Unit Tests
  • Spec Conformance Tests
  • Integration Tests
  • Ballerina By Example Tests
• Increased Test Coverage
• Added necessary documentation
  • API documentation
  • Module documentation in Module.md files
  • Ballerina By Examples

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.05%. Comparing base (3485c88) to head (7fbab37).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...ballerina/cli/task/RestoreCachedArtifactsTask.java	66.66%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #44316      +/-   ##
============================================
+ Coverage     75.02%   75.05%   +0.02%     
- Complexity    58602    58615      +13     
============================================
  Files          3600     3600              
  Lines        226681   226681              
  Branches      29498    29498              
============================================
+ Hits         170071   170129      +58     
+ Misses        47140    47077      -63     
- Partials       9470     9475       +5     

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[NipunaRanasinghe]

LGTM