feature(arch): Add VmArch enum for unified architecture handling across cloud providers

[Copilot]

Refactors architecture handling from AWS-specific AwsArchType to a cloud-agnostic VmArch enum. This implements the first commit from PR #13165, excluding Azure ARM64 gallery split changes per review feedback.

Key Changes:

• VmArch enum (sdcm/provision/provisioner.py):

  • Simple enum with X86 and ARM values
  • Uses built-in enum value constructor (no custom methods needed)
  • Cloud-agnostic with no cloud-specific imports or methods
  • Keeps provisioner.py free of cloud-specific logic

• Cloud-specific conversion utilities (moved out of VmArch per review feedback):

  • vmarch_to_aws() in sdcm/utils/aws_utils.py - converts to AWS format (x86_64/arm64)
  • vmarch_to_gcp() in sdcm/utils/gce_utils.py - converts to GCP format (X86_64/ARM64)
  • vmarch_to_azure() in sdcm/provision/azure/utils.py - converts to Azure format (x64/Arm64)
  • vmarch_to_oci() in sdcm/utils/oci_utils.py - converts to OCI format (x86_64/aarch64)
  • Uses TYPE_CHECKING to avoid circular import issues

• Updated image retrieval functions (sdcm/utils/common.py):

  • All AWS/GCE image functions now accept VmArch instead of AwsArchType
  • Functions use cloud-specific conversion utilities from their respective modules

• CLI updates (sct.py):

  • list_images command accepts arch via click.Choice(["x86_64", "aarch64"])
  • Converts to VmArch using built-in enum value constructor for type-safe cloud API calls

Architecture:
The VmArch enum is now truly cloud-agnostic with conversion logic properly separated into cloud-specific modules. This separation of concerns ensures provisioner.py has no cloud-specific imports or logic, as intended. The implementation leverages Python's standard enum functionality without custom methods.

Not Included:
Azure ARM64 gallery split (separate gallery definitions per architecture) excluded as requested. Azure functions accept arch parameter but receive None - infrastructure ready for future implementation.

Testing

• VmArch conversion methods validated
• Syntax validation passed
• CodeQL security scan: 0 alerts
• No circular import issues
• Built-in enum value constructor works correctly

PR pre-checks (self review)

• I added the relevant backport labels
• I didn't leave commented-out/debugging code

Reminders

• Add New configuration option and document them (in sdcm/sct_config.py)
• Add unit tests to cover my changes (under unit-test/ folder)
• Update the Readme/doc folder relevant to this change (if needed)

Original prompt

redo the first commit from #13165, base on the comment from Lukasz with the PR, leave out the split of using two image definitions in Azure, that should go on it's own PR following

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[fruch]

@copilot I'm missing a convert function for OCI backend

[Copilot]

@copilot I'm missing a convert function for OCI backend

Added vmarch_to_oci() function in sdcm/utils/oci_utils.py that converts VmArch to OCI format (x86_64/aarch64). It follows the same pattern as the AWS, GCP, and Azure conversion functions.

Commit: 756804a