新增 IAwait<T>.repeat 操作符，以支持轮训请求

rxhttp/src/main/java/rxhttp/IAwait.kt

@@ -54,6 +54,34 @@ fun <T> IAwait<T>.retry(
     }
 }
 
+/**
+ * @param times  repeat times, default Long.MAX_VALUE Always repeat
+ * @param period repeat period, default 0, time in milliseconds
+ * @param stop   repeat stop conditions, default false，Unconditional repeat
+ */
+fun <T> IAwait<T>.repeat(
+    times: Long = Long.MAX_VALUE,
+    period: Long = 0,
+    stop: suspend (T) -> Boolean = { false }
+): IAwait<T> = object : IAwait<T> {
+
+    var remaining = if (times == Long.MAX_VALUE) Long.MAX_VALUE else times - 1
+
+    override suspend fun await(): T {
+        while (remaining > 0) {
+            if (remaining != Long.MAX_VALUE) {
+                remaining--
+            }
+            val t = this@repeat.await()
+            if (stop(t)) {
+                return t
+            }
+            kotlinx.coroutines.delay(period)
+        }
+        return this@repeat.await()
+    }
+}
+
 /**
  * Changes the context where this flow is executed to the given [context].
  * This operator is composable and affects only preceding operators that do not have its own context.