Fixed AddDockerFile to work with compute customization

[davidfowl]

Description

• We were not detecting containers with the build annotation and reading the image name from a parameter. Instead, it was using the runtime image name which is incorrect.
• Expose DockerfileBuildAnnotation to make this possible.
• Added test and updated the playground with a docker file sample

Fixes #6439

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-docs issue:
  • No

Microsoft Reviewers: Open in CodeFlow

[davidfowl]

/backport to release/9.0

[github-actions]

Started backporting to release/9.0: https://github.com/dotnet/aspire/actions/runs/11473081084

[github-actions]

@davidfowl backporting to release/9.0 failed, the patch most likely resulted in conflicts:

$ git am --3way --empty=keep --ignore-whitespace --keep-non-patch changes.patch

Applying: Fixed AddDockerFile to work with compute customization - We were not detecting containers with the build annotation and reading the image name from a parameter. Instead, it was using the runtime image name which is incorrect. - Expose DockerfileBuildAnnotation to make this possible. - Added test and updated the playground with a docker file sample
Using index info to reconstruct a base tree...
M	playground/AzureContainerApps/AzureContainerApps.AppHost/Program.cs
M	src/Aspire.Hosting/PublicAPI.Unshipped.txt
M	tests/Aspire.Hosting.Azure.Tests/AzureContainerAppsTests.cs
Falling back to patching base and 3-way merge...
Auto-merging tests/Aspire.Hosting.Azure.Tests/AzureContainerAppsTests.cs
Auto-merging src/Aspire.Hosting/PublicAPI.Unshipped.txt
CONFLICT (content): Merge conflict in src/Aspire.Hosting/PublicAPI.Unshipped.txt
Auto-merging playground/AzureContainerApps/AzureContainerApps.AppHost/Program.cs
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config advice.mergeConflict false"
Patch failed at 0001 Fixed AddDockerFile to work with compute customization - We were not detecting containers with the build annotation and reading the image name from a parameter. Instead, it was using the runtime image name which is incorrect. - Expose DockerfileBuildAnnotation to make this possible. - Added test and updated the playground with a docker file sample
Error: The process '/usr/bin/git' failed with exit code 128

Please backport manually!

[github-actions]

@davidfowl an error occurred while backporting to release/9.0, please check the run log for details!

Error: git am failed, most likely due to a merge conflict.