fix: Fix issues in Ash.Generator.generate_many/2 (#1703)

* docs(`Ash.Generator`): Fix example code blocks to render // correctly

* fix(`Ash.Generator`): Don't error if no `after_action` is provided to `generate_many`

* fix(`Ash.Generator`): Reuse the changeset actor when calling `bulk_create`

* chore(`Ash.Generator`): Read and send notifications created when generating many records

This prevents warnings in tests when using `generate_many` -

`[warning] Missed <x> notifications in action <action>`

* chore(`Ash.Generator`): Raise an error if the `bulk_create` command in `generate_many` wasn't a complete success

A partial success would mean less records were inserted than were requested,
definitely leading to buggy/flaky tests

lib/ash/generator/generator.ex

@@ -12,7 +12,7 @@ defmodule Ash.Generator do
     use Ash.Generator
 
     # using `seed_generator`, bypasses the action and saves directly to the data layer
-    def blog_post(opts \\ []) do
+    def blog_post(opts \\\\ []) do
       seed_generator(
         %MyApp.Blog.Post{
           name: sequence(:title, &"My Blog Post \#{&1}")
@@ -23,7 +23,7 @@ defmodule Ash.Generator do
     end
 
     # using `changeset_generator`, calls the action when passed to `generate`
-    def blog_post_comment(opts \\ []) do
+    def blog_post_comment(opts \\\\ []) do
       blog_post_id = opts[:blog_post_id] || once(:default_blog_post_id, fn -> generate(blog_post()).id end)
 
       changeset_generator(
@@ -505,12 +505,27 @@ defmodule Ash.Generator do
             fn _changeset, record ->
               {:ok, after_action.(record)}
             end
+          else
+            # Do nothing
+            fn _changeset, record -> {:ok, record} end
           end
 
-        Ash.bulk_create!(Enum.map(batch, & &1.params), first.resource, first.action,
-          after_action: after_action,
-          return_records?: true
-        ).records || []
+        result =
+          Ash.bulk_create!(Enum.map(batch, & &1.params), first.resource, first.action.name,
+            after_action: after_action,
+            return_records?: true,
+            return_errors?: true,
+            return_notifications?: true,
+            actor: first.context[:private][:actor]
+          )
+
+        if result.status != :success do
+          raise Ash.Error.to_error_class(result.errors)
+        end
+
+        Ash.Notifier.notify(result.notifications)
+
+        result.records || []
 
       batch ->
         Enum.map(batch, fn record ->
@@ -641,7 +656,7 @@ defmodule Ash.Generator do
   Generate input meant to be passed into `Ash.Seed.seed!/2`.
 
   A map of custom `StreamData` generators can be provided to add to or overwrite the generated input,
-  for example: `Ash.Generator.for_seed(Post, %{text: StreamData.constant("Post")})`
+  for example: `Ash.Generator.seed_input(Post, %{text: StreamData.constant("Post")})`
   """
   @spec seed_input(Ash.Resource.t(), map()) :: StreamData.t(map())
   def seed_input(resource, generators \\ %{}) do