[storage] Add warning message for account migration cmdlet

[VeryEarly]

Description

sync future branch: #26794

• Added warning message for account migration cmdlet.
  • Start-AzStorageAccountMigration

Mandatory Checklist

• Please choose the target release of Azure PowerShell. (⚠️Target release is a different concept from API readiness. Please click below links for details.)

  • General release
  • Public preview
  • Private preview
  • Engineering build
  • No need for a release

• Check this box to confirm: I have read the Submitting Changes section of CONTRIBUTING.md and reviewed the following information:

• SHOULD update ChangeLog.md file(s) appropriately
  • For SDK-based development mode, update src/{{SERVICE}}/{{SERVICE}}/ChangeLog.md.
    • A snippet outlining the change(s) made in the PR should be written under the ## Upcoming Release header in the past tense.
  • For autorest-based development mode, include the changelog in the PR description.
  • Should not change ChangeLog.md if no new release is required, such as fixing test case only.
• SHOULD regenerate markdown help files if there is cmdlet API change. Instruction
• SHOULD have proper test coverage for changes in pull request.
• SHOULD NOT adjust version of module manually in pull request

[azure-client-tools-bot-prd]

️✔️Az.Accounts

️✔️Build

️✔️PowerShell Core - Windows

⚠️Az.Storage

️✔️Build

️✔️PowerShell Core - Windows

️✔️Breaking Change Check

️✔️PowerShell Core - Windows

⚠️Signature Check

⚠️PowerShell Core - Windows

Type	Cmdlet	Description	Remediation
⚠️	Get-AzStorageAccountMigration	Get-AzStorageAccountMigration Changes the ConfirmImpact but does not set the SupportsShouldProcess property to true in the cmdlet attribute.	Determine if the cmdlet should implement ShouldProcess and if so determine if it should implement Force / ShouldContinue
⚠️	Get-AzStorageAccountMigration	Get-AzStorageAccountMigration changes the confirm impact. Please ensure that the change in ConfirmImpact is justified	Verify that ConfirmImpact is changed appropriately by the cmdlet. It is very rare for a cmdlet to change the ConfirmImpact.

️✔️Help Example Check

️✔️PowerShell Core - Windows

️✔️Help File Existence Check

️✔️PowerShell Core - Windows

⚠️File Change Check

⚠️PowerShell Core - Windows

Type	Cmdlet	Description	Remediation
⚠️		AssemblyInfo.cs will be updated automatically. Please do not update it manually.	Revert AssemblyInfo.cs to its last version.
⚠️		It is required to update ChangeLog.md if you want to release a new version for Az.Storage.	Add a changelog record under Upcoming Release section with past tense.

️✔️UX Metadata Check

️✔️PowerShell Core - Windows

⚠️Test

⚠️ - Linux

Type	Title	Current Coverage	Description
⚠️	Test Coverage Less Than 50%	0.59 %	Test coverage for the module cannot be lower than 50%.

⚠️ - MacOS

Type	Title	Current Coverage	Description
⚠️	Test Coverage Less Than 50%	0.59%	Test coverage for the module cannot be lower than 50%.

⚠️PowerShell Core - Windows

Type	Title	Current Coverage	Description
⚠️	Test Coverage Less Than 50%	0.59%	Test coverage for the module cannot be lower than 50%.

not ready