Address second round of review feedback

...n/org/briarproject/briar/desktop/forums/AddForumDialog.kt

...kotlin/org/briarproject/briar/desktop/forums/ForumItem.kt

...n/org/briarproject/briar/desktop/forums/ForumViewModel.kt

...kotlin/org/briarproject/briar/desktop/forums/GroupCard.kt

...tlin/org/briarproject/briar/desktop/forums/GroupCircle.kt

...arproject/briar/desktop/forums/GroupConversationScreen.kt

...otlin/org/briarproject/briar/desktop/forums/ThreadItem.kt

...rg/briarproject/briar/desktop/threading/BriarExecutors.kt

...riarproject/briar/desktop/threading/BriarExecutorsImpl.kt

...n/org/briarproject/briar/desktop/viewmodel/DbViewModel.kt

...esktop/src/main/resources/strings/BriarDesktop.properties