added private link and removed tuple/Pair

[tanmaya-panda1]

This pull request introduces a new S2SToken model to standardize Service-to-Service (S2S) authentication for Fabric Private Link scenarios and refactors related APIs to use this model instead of a generic token pair. Additionally, it improves the upload stream preparation logic by introducing a helper class for better code clarity and maintainability.

Authentication and Fabric Private Link Refactor:

• Introduced the S2SToken data class to encapsulate both the authentication scheme and token value, with helper methods for formatting and creation.
• Updated all S2S token provider signatures and usages throughout the API, builders, and configuration cache to use S2SToken instead of a Pair<String, String>, ensuring type safety and clarity. [1] [2] [3] [4]
• Passed the new S2S token provider and Fabric Private Link access context through all relevant constructors and builder methods, including ConfigurationClient, KustoBaseApiClient, and ingest client builders. [1] [2] [3] [4]
• Refactored the HTTP header construction for S2S authentication to use the new S2SToken.toHeaderValue() method, simplifying and unifying header formatting.

Upload Stream Preparation Improvements:

• Replaced the use of a Triple for upload stream preparation with a dedicated PreparedUploadStream data class, improving code readability and maintainability in ContainerUploaderBase. [1] [2] [3]

These changes provide a more robust and maintainable approach to handling S2S authentication and upload stream preparation, paving the way for future enhancements and reducing potential errors.### Added

Changed

Fixed

[github-actions]

Test Results

530 tests  ±0   521 ✅ ±0   8m 18s ⏱️ +4s
 31 suites ±0     9 💤 ±0 
 31 files   ±0     0 ❌ ±0 

Results for commit 7802103. ± Comparison against base commit b1ec311.

[github-actions]

Test Results

530 tests  ±0   521 ✅ ±0   8m 3s ⏱️ -11s
 31 suites ±0     9 💤 ±0 
 31 files   ±0     0 ❌ ±0 

Results for commit 7802103. ± Comparison against base commit b1ec311.

[github-actions]

Test Results

530 tests  ±0   521 ✅ ±0   8m 12s ⏱️ -2s
 31 suites ±0     9 💤 ±0 
 31 files   ±0     0 ❌ ±0 

Results for commit 7802103. ± Comparison against base commit b1ec311.