Crash when sending a friend request with a long message

[robinlinden]

Instead of crashing, we want some validation with nice UI feedback, similar to how the ToxID entry will tell people off if the ID is invalid.

im.tox.tox4j.core.exceptions.ToxFriendAddException: Error code: TOO_LONG
    at im.tox.tox4j.impl.jni.ToxCoreJni.toxFriendAdd(Native Method)
    at im.tox.tox4j.impl.jni.ToxCoreImpl.addFriend(ToxCoreImpl.scala:201)
    at ltd.evilcorp.domain.tox.ToxWrapper.addContact-cVeOlmQ(ToxWrapper.kt:96)
    at ltd.evilcorp.domain.tox.Tox.addContact-cVeOlmQ(Tox.kt:194)
    at ltd.evilcorp.domain.feature.ContactManager$add$1.invokeSuspend(ContactManager.kt:27)
    at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
    at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:101)
    at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:589)
    at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.kt:832)
    at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.kt:720)
    at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:707)
    Suppressed: kotlinx.coroutines.internal.DiagnosticCoroutineContextException: [StandaloneCoroutine{Cancelling}@8321ffa, Dispatchers.Default]