Add missing dedicaated server methods

[kzaitsev]

Add missing dedicated server update fields and extend host management API

Changes

pkg/types.go

• Extended DedicatedServerUpdateInput with two new fields:
  • UserData *string — cloud-init user data, processed during next server initialization; pointer type allows explicit clearing via empty string while omitting the field when not provided
  • IPXEConfig *string — iPXE boot configuration (currently under development)
• Added new input types:
  • HostRescueModeFeatureInput — AuthMethods []string, SSHKeyFingerprints []string
  • PrivateIpxeBootFeatureInput — IPXEConfig string
  • SSHKeyAttachInput — SSHkeyFingerprints []string

pkg/hosts.go

• Added HostsService interface methods and implementations for dedicated server feature management:
  • ActivateDisaggregatedPublicPortsFeature / DeactivateDisaggregatedPublicPortsFeature
  • ActivateDisaggregatedPrivatePortsFeature / DeactivateDisaggregatedPrivatePortsFeature
  • ActivateNoPublicIpAddressFeature / DeactivateNoPublicIpAddressFeature
  • ActivateNoPrivateIpFeature / DeactivateNoPrivateIpFeature
  • ActivateOobPublicAccessFeature / DeactivateOobPublicAccessFeature
  • ActivateNoPublicNetworkFeature / DeactivateNoPublicNetworkFeature
  • ActivateHostRescueModeFeature / DeactivateHostRescueModeFeature — rescue mode requires HostRescueModeFeatureInput (auth methods + optional SSH key fingerprints)
  • ActivatePrivateIpxeBootFeature / DeactivatePrivateIpxeBootFeature — requires PrivateIpxeBootFeatureInput (iPXE config string)
• Added SSH key binding methods for dedicated servers:
  • ListDedicatedServerSSHKeys — returns all SSH keys attached to a server
  • AttachSSHKeysToDedicatedServer — attaches one or more keys via SSHKeyAttachInput
  • DetachSSHKeyFromDedicatedServer — detaches a single key by fingerprint

pkg/hosts_test.go / pkg/fixtures/

• Added tests and fixtures for all new feature activate/deactivate methods and SSH key binding operations