Further test coverage improvements

...de/justjanne/libquassel/protocol/models/BufferActivity.kt

...stjanne/libquassel/protocol/syncables/BufferViewConfig.kt

...tjanne/libquassel/protocol/syncables/IgnoreListManager.kt

.../de/justjanne/libquassel/protocol/syncables/IrcChannel.kt

...quassel/protocol/syncables/state/BufferViewConfigState.kt

...bquassel/protocol/syncables/stubs/BufferViewConfigStub.kt

...de/justjanne/libquassel/protocol/util/collections/move.kt

.../justjanne/libquassel/protocol/util/collections/remove.kt

...nne/libquassel/protocol/syncables/BufferViewConfigTest.kt

...ne/libquassel/protocol/syncables/BufferViewManagerTest.kt

...libquassel/protocol/syncables/HighlightRuleManagerTest.kt

...ne/libquassel/protocol/syncables/IgnoreListManagerTest.kt

...justjanne/libquassel/protocol/syncables/IrcChannelTest.kt

...otlin/de/justjanne/libquassel/protocol/testutil/Random.kt

...ustjanne/libquassel/protocol/util/collections/MoveTest.kt