✨ Add native async logger adapter package

bitlogger_async/async_logger_stub.mbt

@@ -0,0 +1,36 @@
+pub(all) suberror AsyncLoggerClosed {
+  AsyncLoggerClosed
+}
+
+pub(all) enum AsyncOverflowPolicy {
+  Blocking
+  DropOldest
+  DropNewest
+}
+
+pub struct AsyncLoggerConfig {
+  max_pending : Int
+  overflow : AsyncOverflowPolicy
+}
+
+pub fn AsyncLoggerConfig::new(
+  max_pending~ : Int = 0,
+  overflow~ : AsyncOverflowPolicy = AsyncOverflowPolicy::Blocking,
+) -> AsyncLoggerConfig {
+  { max_pending, overflow }
+}
+
+pub struct AsyncLogger[S] {}
+
+pub fn async_logger[S : @bitlogger.Sink](
+  sink : S,
+  config~ : AsyncLoggerConfig = AsyncLoggerConfig::new(),
+  min_level~ : @bitlogger.Level = @bitlogger.Level::Info,
+  target~ : String = "",
+) -> AsyncLogger[S] {
+  ignore(sink)
+  ignore(config)
+  ignore(min_level)
+  ignore(target)
+  abort("bitlogger_async currently only supports native/llvm backends")
+}