clean up the kotlin compiler warnings

[K0zka]

There are 13 compiler warnings at the moment, it would be nice to have 0

/home/kocka/sources/kerub/src/test/kotlin/com/github/K0zka/kerub/host/ControllerManagerImplTest.kt
Warning:(34, 9) Kotlin: Variable 'controllerDynamic' is never used
/home/kocka/sources/kerub/src/test/kotlin/com/github/K0zka/kerub/host/HostCapabilitiesDiscovererTest.kt
Warning:(98, 45) Kotlin: Elvis operator (?:) always returns the left operand of non-nullable type kotlin.Long
Warning:(98, 53) Kotlin: Unnecessary safe call on a non-null receiver of type kotlin.String
Warning:(98, 63) Kotlin: Unnecessary safe call on a non-null receiver of type kotlin.Int
Warning:(153, 42) Kotlin: This syntax for lambda is deprecated. Use short lambda notation {a[: Int], b[: String] -> ...} or function expression instead.
Warning:(175, 7) Kotlin: Variable 'host' is never used
Warning:(181, 48) Kotlin: Unnecessary non-null assertion (!!) on a non-null receiver of type com.github.K0zka.kerub.host.HostCapabilitiesDiscoverer
Warning:(183, 40) Kotlin: Unnecessary safe call on a non-null receiver of type com.github.K0zka.kerub.model.HostCapabilities
Warning:(184, 45) Kotlin: Unnecessary safe call on a non-null receiver of type com.github.K0zka.kerub.model.HostCapabilities
/home/kocka/sources/kerub/src/test/kotlin/com/github/K0zka/kerub/host/SshClientUtilsTest.kt
Warning:(54, 37) Kotlin: This syntax for lambda is deprecated. Use short lambda notation {a[: Int], b[: String] -> ...} or function expression instead.
Warning:(64, 33) Kotlin: This syntax for lambda is deprecated. Use short lambda notation {a[: Int], b[: String] -> ...} or function expression instead.
/home/kocka/sources/kerub/src/test/kotlin/com/github/K0zka/kerub/hypervisor/kvm/UtilsTest.kt
Warning:(25, 7) Kotlin: Variable 'dom' is never used
/home/kocka/sources/kerub/src/test/kotlin/com/github/K0zka/kerub/utils/junix/dmi/DmiDecoderTest.kt
Warning:(127, 7) Kotlin: Variable 'devices' is never used

[K0zka]

there are 4 left:

• 3 of these from nullable parameter types - open issue in kotlin KT-153
• the fourth is an unfinished feature, work in prg