Update AGP to 8.0

Co-authored-by: Greyson Parrelli <greyson@signal.org>

core-util/src/main/java/org/signal/core/util/concurrent/MaybeCompat.kt

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2023 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.signal.core.util.concurrent
+
+import io.reactivex.rxjava3.core.Maybe
+import io.reactivex.rxjava3.exceptions.Exceptions
+import io.reactivex.rxjava3.plugins.RxJavaPlugins
+
+/**
+ * Kotlin 1.8 started respecting RxJava nullability annotations but RxJava has some oddities where it breaks those rules.
+ * This essentially re-implements [Maybe.fromCallable] with an emitter so we don't have to do it everywhere ourselves.
+ */
+object MaybeCompat {
+  fun <T : Any> fromCallable(callable: () -> T?): Maybe<T> {
+    return Maybe.create { emitter ->
+      val result = try {
+        callable()
+      } catch (e: Throwable) {
+        Exceptions.throwIfFatal(e)
+        if (!emitter.isDisposed) {
+          emitter.onError(e)
+        } else {
+          RxJavaPlugins.onError(e)
+        }
+        return@create
+      }
+
+      if (!emitter.isDisposed) {
+        if (result == null) {
+          emitter.onComplete()
+        } else {
+          emitter.onSuccess(result)
+        }
+      }
+    }
+  }
+}