adds guest manager interfaces + implementation for guest operations

[rawahars]

This pull request introduces a new guest-side management layer for virtual machines (VMs), clearly separating guest operations from host-side management and configuration. It does so by defining new interfaces and concrete implementations for interacting with the guest via the Guest Compute Service (GCS).

Note This PR is dependent upon #2597

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The most important changes are:

Guest Manager Interface and Implementation:

• Introduced the GuestOps interface in internal/vm/guest.go, which defines APIs for establishing a GCS connection and performing guest-side operations (network, storage, device, security policy, etc.). This interface is the contract for guest management.
• Added a new guestManager implementation of GuestOps in internal/vm/guestmanager/hcs.go, which manages the GCS connection lifecycle, applies configuration options, and exposes guest-side management interfaces.

Guest Resource Management Implementations:

• Implemented concrete guest-side managers for:
  • Network operations (GuestNetworkManager) in internal/vm/guestmanager/network.go
  • Directory mapping (DirectoryManager) in internal/vm/guestmanager/mapped_directory.go
  • Combined layers management (LayersManager) in internal/vm/guestmanager/combinedlayers.go
  • Device management (GuestDeviceManager) in internal/vm/guestmanager/device.go
  • Block CIMs management (BlockCIMsManager) in internal/vm/guestmanager/block_cims.go

This refactor lays a foundation for clean separation between host and guest responsibilities.