Remove launch_storyboard from tvos_application.

Apple's docs don't call it out, but the best I can tell:

https://developer.apple.com/ios/human-interface-guidelines/icons-and-images/
https://developer.apple.com/tvos/human-interface-guidelines/icons-and-images/

On tvOS it has a sub section titled "Launch Image", which only talks about images.
On iOS it has a sub section titled "Launch Screen", which talks about storyboards or images.

All of the Xcode 9.3 templates start out with launch image support.

The one possible source of confusion is they use a main storyboard for their ui.

PiperOrigin-RevId: 193385625

apple/bundling/tvos_rules.bzl

@@ -50,13 +50,9 @@ def _tvos_application_impl(ctx):
     bundling_support.ensure_single_xcassets_type(
         "launch_images", launch_images, "launchimage")
 
-  # Collect asset catalogs, launch images, and the launch storyboard, if any are
-  # present.
+  # Collect asset catalogs and launch images, if any are present.
   additional_resource_sets = []
   additional_resources = depset(app_icons + launch_images)
-  launch_storyboard = ctx.file.launch_storyboard
-  if launch_storyboard:
-    additional_resources += [launch_storyboard]
   if additional_resources:
     additional_resource_sets.append(AppleResourceSet(
         resources=additional_resources,
@@ -113,10 +109,6 @@ tvos_application = rule_factory.make_bundling_rule(
             providers=[[AppleBundleInfo, TvosExtensionBundleInfo]],
         ),
         "launch_images": attr.label_list(allow_files=True),
-        "launch_storyboard": attr.label(
-            allow_files=[".storyboard", ".xib"],
-            single_file=True,
-        ),
         "settings_bundle": attr.label(providers=[["objc"]]),
     },
     archive_extension=".ipa",

apple/tvos.bzl

@@ -74,11 +74,6 @@ def tvos_application(name, **kwargs):
         Each file must have a containing directory named
         `"*.xcassets/*.launchimage"` and there may be only one such
         `.launchimage` directory in the list.
-    launch_storyboard: The `.storyboard` or `.xib` file that should be used as
-        the launch screen for the application. The provided file will be
-        compiled into the appropriate format and placed in the root of the
-        final bundle. The generated file is registered in the final bundle's
-        `Info.plist` under the key `UILaunchStoryboardName`.
     linkopts: A list of strings representing extra flags that the underlying
         `apple_binary` target should pass to the linker.
     provisioning_profile: The provisioning profile (`.mobileprovision` file) to

doc/rules-tvos.md

@@ -6,8 +6,8 @@
 ```python
 tvos_application(name, app_icons, bundle_id, bundle_name, entitlements,
 entitlements_validation, extensions, infoplists, ipa_post_processor,
-launch_images, launch_storyboard, linkopts, minimum_os_version,
-provisioning_profile, settings_bundle, strings, version, deps)
+launch_images, linkopts, minimum_os_version, provisioning_profile,
+settings_bundle, strings, version, deps)
 ```
 
 Builds and bundles a tvOS application.
@@ -120,20 +120,6 @@ Builds and bundles a tvOS application.
         <p>Files that comprise the launch images for the application. Each file
         must have a containing directory named<code>*.xcassets/*.launchimage</code> and
         there may be only one such <code>.launchimage</code> directory in the list.</p>
-        <p>It is recommended that you use a <code>launch_storyboard</code> instead if
-        you are targeting only iOS 8 and later.</p>
-      </td>
-    </tr>
-    <tr>
-      <td><code>launch_storyboard</code></td>
-      <td>
-        <p><code><a href="https://bazel.build/versions/master/docs/build-ref.html#labels">Label</a>; optional</code></p>
-        <p>The <code>.storyboard</code> or <code>.xib</code> file that should
-        be used as the launch screen for the application. The provided file will
-        be compiled into the appropriate format (<code>.storyboardc</code> or
-        <code>.nib</code>) and placed in the root of the final bundle. The
-        generated file will also be registered in the bundle's <code>Info.plist</code>
-        under the key <code>UILaunchStoryboardName</code>.</p>
       </td>
     </tr>
     <tr>