Port PR #15599 to main: Add native arm64 build targets to CI pipeline

[Copilot]

Description

Port of #15599 to main (squashed commit).

Adds native arm64 build targets to the CI pipeline so the dogfood script and release bundles include arm64 CLI binaries:

• linux-arm64 on ubuntu-24.04-arm runner
• win-arm64 on windows-11-arm runner

Changes

• build-cli-native-archives.yml: Add linux-arm64 and win-arm64 to the default targets matrix; fix job name to use matrix.targets.rids instead of matrix.targets.os to avoid duplicate names when multiple targets share the same OS value.
• run-tests.yml: Fix RID computation to use runner.os + runner.arch instead of hardcoding linux-x64/win-x64, so tests on arm64 runners download the correct arch-specific NuGet packages.
• tests.yml: Add build_cli_archive_linux_arm64 and build_cli_archive_windows_arm64 jobs; replace the conditional build_cli_archive_windows_arm job with the unconditional build_cli_archive_windows_arm64; add arm64 jobs to the results gate.
• Various .csproj files: Add Grpc.Tools VersionOverride="2.68.1" PrivateAssets="all" to fix arm64 build issues.

Fixes # (issue)

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No
• Does the change require an update in our Aspire docs?
  • Yes
    • Link to aspire.dev issue:
      • New issue
  • No