Add x-azcopy and x-azcopy-sas binary caching sources

[vicroms]

Adds two new binary sources that interact with Azure Storage blob containers using the azcopy executable.

• x-azcopy-sas,<url>,<sas>[,<rw>]: Intended as a drop-in replacement for azblob, it uses SAS tokens for authentication.
• x-azcopy,<url>[,<rw>]: Intended for non-SAS authentication methods like Microsoft Entra ID; requires preloading credentials or/and the AZCOPY_AUTO_LOGIN_TYPE.

Internally, we use azcopy copy --from-to BlobLocal {destination} --include-path {files} argument to download multiple files in a single azcopy job, this improves performance and brings it more in line with azblob, that uses a single curl invocation to download a batch of files. Upload happens one file at a time in the background.

Small test

x-azblob:
    Restored 5 package(s) from HTTP servers in 3.8 s. Use --debug to see more details.

x-azcopy:
    Restored 5 package(s) from Azure Storage in 1.5 min. Use --debug to see more details.

x-azcopy-sas:
    Restored 5 package(s) from Azure Storage in 4.7 s. Use --debug to see more details.

Large test

azcopy-sas (with --include-path):
    Restored 141 package(s) from Azure Storage in 1.5 min. Use --debug to see more details.

azblob:
    Restored 141 package(s) from HTTP servers in 3 min. Use --debug to see more details.

Related:

• End-to-end tests:
  • Restore packages: [DO NOT MERGE] Test x-azcopy and x-azcopy-sas binary cache sources. vcpkg#46705, results: https://dev.azure.com/vcpkg/public/_build/results?buildId=118599&view=results
  • Large blobs: [invalid] Test uploads with azcopy vcpkg#45461, results: https://dev.azure.com/vcpkg/public/_build/results?buildId=118645&view=results
• Documentation (PR: Docs for x-azcopy and x-azcopy-sas binary caching sources MicrosoftDocs/vcpkg-docs#511)

[vicroms]

Back to draft while the x64-osx upload failures are being investigated: https://dev.azure.com/vcpkg/public/_build/results?buildId=118621&view=logs&j=7b75bd19-17d3-53d4-00fd-23f1a49a8ba4&t=c0c57043-5abe-5a13-5ef1-aa66ea261ab3&l=95

[BillyONeal]

The only comment I'm 'request changes' over is the one on line 1078 where the for loop seems clearly broken. The other things are nitpicks.

[Copilot]

Pull Request Overview

This PR adds two new binary caching sources for vcpkg that use Azure Storage blob containers via the azcopy executable. The implementation provides both SAS token-based authentication and Microsoft Entra ID authentication options.

Key changes:

• Introduces x-azcopy and x-azcopy-sas binary cache providers as alternatives to existing Azure blob storage options
• Implements batch downloading using azcopy copy --include-path for improved performance compared to individual file downloads
• Adds comprehensive test coverage for both new provider types with various configuration scenarios

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/vcpkg/metrics.cpp	Adds metrics tracking for the two new azcopy binary cache providers
src/vcpkg/binarycaching.cpp	Core implementation of AzCopy providers with batch download/upload logic and configuration parsing
src/vcpkg-test/configparser.cpp	Comprehensive unit tests for both azcopy provider variants with various configuration scenarios
locales/messages.json	Adds localized message for Azure Storage restoration feedback
include/vcpkg/metrics.h	Defines new metric types for tracking azcopy provider usage
include/vcpkg/binarycaching.h	Declares AzCopyUrl structure and adds provider state fields
include/vcpkg/base/message-data.inc.h	Declares the new Azure Storage restoration message

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