[Image Copy] Fix snapshot create issue

[qwordy]

This issue is due to a breaking change of snapshot service. The service changed a parameter (source storage account ID) from optional to mandatory recently. This PR infers source storage account ID automatically to fix this issue. Breaking change is catastrophic.

Fix issue Azure/azure-cli#11625

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General Guidelines

• Have you run azdev style <YOUR_EXT> locally? (pip install azdev required)
• Have you run python scripts/ci/test_index.py -q locally?

For new extensions:

• My extension description/summary conforms to the Extension Summary Guidelines.

[azuresdkci]

If this PR is for a new extension or change to an existing extension, use the following to try out the changes in this PR:

docker run -it microsoft/azure-cli:latest
export EXT=<NAME>
pip install --upgrade --target ~/.azure/cliextensions/$EXT "git+https://github.com/qwordy/azure-cli-extensions.git@11625#subdirectory=src/$EXT&egg=$EXT"

[yungezz]

is this original service behavior? otherwise, pls help to document the behavior.

[qwordy]

The goal of this PR is to infer storage account ID. If target_subscription is None, use the default subscription.
Code that creates storage account.

cli_cmd = prepare_cli_command(['storage', 'account', 'create',
                                   '--name', target_storage_account_name,
                                   '--resource-group', transient_resource_group_name,
                                   '--location', location,
                                   '--sku', 'Standard_LRS'],
                                  subscription=target_subscription)

[yungezz]

the scenario: no specifying target_subscription is covered by test, right? and it doesn't fail because run only in recorded way, but not live run, right?

[qwordy]

the scenario: no specifying target_subscription is covered by test, right? and it doesn't fail because run only in recorded way, but not live run, right?

This issue is caused by a breaking change in service. There is no automatic testing in this module. I test manually. I made the minimal change to fix issue 11625. "target_subscription" is not the focus of this issue and PR.

[yungezz]

the scenario: no specifying target_subscription is covered by test, right? and it doesn't fail because run only in recorded way, but not live run, right?

This issue is caused by a breaking change in service. There is no automatic testing in this module. I test manually. I made the minimal change to fix issue 11625. "target_subscription" is not the focus of this issue and PR.

fix typo. source-storage-account-id :) . there's test to cover source-storage-account-id none?

[qwordy]

OK. I can add a test case for this PR although there is no testing in this module now.

[tamirkamara]

LGTM.