Migrated login, login status and logout to library

[gapra-msft]

No description provided.

[Copilot]

Pull Request Overview

This PR refactors authentication-related functionality by migrating login, logout, and login status operations from the cmd package to a centralized azcopy library. This consolidation improves code organization and reusability by moving business logic out of command handlers.

Key Changes:

• Created new azcopy/loginlogout.go file with Login(), Logout(), and GetLoginStatus() methods on the Client type
• Refactored command handlers in cmd/login.go, cmd/logout.go, and cmd/loginStatus.go to call the new library methods
• Moved LoginOptions type definition from cmd to common package and aliased it in azcopy package

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
azcopy/loginlogout.go	New file implementing centralized login, logout, and status check methods on Client
cmd/login.go	Simplified to delegate login logic to library; moved environment variable handling to toOptions()
cmd/logout.go	Removed local RunLogout() and process() methods; now calls Client.Logout()
cmd/loginStatus.go	Removed local status processing; now calls Client.GetLoginStatus() and references LoginType instead of AuthMethod

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