Fix unresolved theme attributes exception

[bemusementpark]

This PR avoids throwing/logging this exception.

2023-09-13 14:20:42.739  8485-8485  Resources               network.loki.messenger               W  Drawable network.loki.messenger:drawable/avatar_gradient_dark has unresolved theme attributes! Consider using Resources.getDrawable(int, Theme) or Context.getDrawable(int).
                                                                                                    java.lang.RuntimeException
                                                                                                    	at android.content.res.Resources.getDrawable(Resources.java:908)
                                                                                                    	at org.session.libsession.avatars.ResourceContactPhoto.asDrawable(ResourceContactPhoto.java:42)
                                                                                                    	at org.thoughtcrime.securesms.components.ProfilePictureView$unknownRecipientDrawable$2.invoke(ProfilePictureView.kt:38)
                                                                                                    	at org.thoughtcrime.securesms.components.ProfilePictureView$unknownRecipientDrawable$2.invoke(ProfilePictureView.kt:37)
                                                                                                    	at kotlin.SynchronizedLazyImpl.getValue(LazyJVM.kt:74)
                                                                                                    	at org.thoughtcrime.securesms.components.ProfilePictureView.getUnknownRecipientDrawable(ProfilePictureView.kt:37)
                                                                                                    	at org.thoughtcrime.securesms.components.ProfilePictureView.setProfilePictureIfNeeded(ProfilePictureView.kt:144)
                                                                                                    	at org.thoughtcrime.securesms.components.ProfilePictureView.update(ProfilePictureView.kt:102)
                                                                                                    	at org.thoughtcrime.securesms.components.ProfilePictureView.update(ProfilePictureView.kt:86)
                                                                                                    	at org.thoughtcrime.securesms.home.ConversationView.bind(ConversationView.kt:127)
                                                                                                    	at org.thoughtcrime.securesms.home.HomeAdapter.onBindViewHolder(HomeAdapter.kt:100)
                                                                                                    	at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:7254)