Refactor VM lifecycle management and enhance validation

- Introduced a new method `installed_kernel` in `ImageStore` to handle kernel verification and checksum validation.
- Updated `Installer` to include additional packages: `nftables` and `conntrack`.
- Refined `LifecycleService` to improve error handling and state management during VM creation, starting, stopping, and deletion.
- Enhanced port management with new methods for setting and syncing ports, including validation for port rules.
- Improved error handling in `StateStore` to raise specific `NotFoundError` and `ConflictError` exceptions.
- Updated network management to ensure proper TAP device handling and firewall integration.
- Enhanced API responses in `vms.py` to include policy status for better client-side handling.
- Added validation for VM names and ports in `validation.py` to enforce stricter rules and prevent conflicts.

uvm/errors.py

@@ -23,6 +23,14 @@ class StateError(UvmError):
     """Raised when persisted VM state cannot be safely used."""
 
 
+class NotFoundError(UvmError):
+    """A requested registry entry does not exist."""
+
+
+class ConflictError(UvmError):
+    """An allocation or pending operation prevents the requested action."""
+
+
 class CommandError(UvmError):
     """Raised when a required host command cannot be executed successfully."""