feat(bus): allow adding multiple jobs to chain (#55668)

`prependToChain()` reverses the collection before inserting the jobs one
by one to ensure that the first job is processed before the second one.

Author: dallyger

src/Illuminate/Bus/Queueable.php

@@ -221,9 +221,11 @@ public function chain($chain)
      */
     public function prependToChain($job)
     {
-        $jobs = ChainedBatch::prepareNestedBatches(new Collection([$job]));
+        $jobs = ChainedBatch::prepareNestedBatches(Collection::wrap($job));
 
-        $this->chained = Arr::prepend($this->chained, $this->serializeJob($jobs->first()));
+        foreach ($jobs->reverse() as $job) {
+            $this->chained = Arr::prepend($this->chained, $this->serializeJob($job));
+        }
 
         return $this;
     }
@@ -236,9 +238,11 @@ public function prependToChain($job)
      */
     public function appendToChain($job)
     {
-        $jobs = ChainedBatch::prepareNestedBatches(new Collection([$job]));
+        $jobs = ChainedBatch::prepareNestedBatches(Collection::wrap($job));
 
-        $this->chained = array_merge($this->chained, [$this->serializeJob($jobs->first())]);
+        foreach ($jobs as $job) {
+            $this->chained = array_merge($this->chained, [$this->serializeJob($job)]);
+        }
 
         return $this;
     }