Adding Azure Local Support

[SethBe]

Azure Local Attestation Support

This PR adds Azure Local support for the guest attestation client library and sample applications.

Changes

Client Library – Azure Local build option (-DAZURE_LOCAL)

• Introduces a CMake build flag (AZURE_LOCAL) that conditionally compiles the client library to use the edge-cc-base-attestation-sdk instead of IMDS for retrieving endorsements (VCek certificate).
• The SDK is currently published to the Insider's Fast ring; a helper script (enable-insider-fast-repo.sh) is provided to configure the package source.

PCR 11 inclusion

• When built for Azure Local, PCR 11 is added to the attested PCR list to ensure disk integrity verification. This aligns with upcoming Azure Local image-generation guidance.

Build & prerequisite scripts

• azurelocal/build-azure-local.sh – single entry-point script that builds the client library, attestation sample app, and SKR sample app for Azure Local. Supports clean rebuilds (-c) and prerequisite installation (-p).
• cvm-attestation-sample-app/ClientLibBuildAndInstallAzureLocal.sh – builds and installs the client library with the Azure Local flag.
• client-library/src/Attestation/pre-requisites-azure-local.sh – installs Azure Local-specific dependencies.

Sample application support

• Both the attestation sample app (cvm-attestation-sample-app) and the Secure Key Release sample app (cvm-securekey-release-app) are supported (without managed identity).
• Updated READMEs with Azure Local build and usage instructions.

Notes

• Azure Local is currently in development and subject to change.