fix: Silent failure of DockerAgent's push_image(), pull_image()

[jopemachine]

This PR modifies the behavior of the DockerAgent so that when an error occurs during the execution of push_image() or pull_image(), it does not fail silently but instead informs the user that an issue has occurred.

Test

Tested manually.
For example, when incorrect Docker credentials are used, it will raise an error like below.

❯ ./backend.ai session convert-to-image 7a6b642b-22f4-42fd-b6fb-bbdf2a818ba3 new-img
∙ Request to commit Session(name or id: 7a6b642b-22f4-42fd-b6fb-bbdf2a818ba3)
 33%|███████████████████████████████████████████████████████████                                                                                                                      | 1/3 [00:02<00:04,  2.01s/it]
✗ Error during the operation: <BackendError(-1): General Backend API Error. (RuntimeError("Failed to push image: unauthorized: HTTP Basic: Access denied. If a password was provided for Git authentication, the password was incorrect or you're required to use a token instead of a password. If a token was provided, it was either incorrect, expired, or improperly scoped. See https://gitlab.com/help/user/profile/account/two_factor_authentication.md#troubleshooting"))>

Checklist: (if applicable)

• Milestone metadata specifying the target backport version
• Mention to the original issue
• Test case(s) to:
  • Demonstrate the difference of before/after
  • Demonstrate the flow of abstract/conceptual models with a concrete implementation

[jopemachine]

• fix: Silent failure of DockerAgent's push_image(), pull_image() #2572 👈 (View in Graphite)
• fix: Missing notification of bgtask cancellation or failure when shutting down the server #2579
• main

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[jopemachine]

In addition to modifying the push_image code, it appears that other aiodocker API calls, such as pull_image, also need to be revised.

[jopemachine]

In this PR, I found several incorrect return types in aiodocker, which led me to create the PR below.
aio-libs/aiodocker#909.

Until the above PR is merged, I’ll manually cast these types to list and leave TODO comments as reminders.

[HyeockJinKim]

lgtm