Fixes keystone_app_name value collision.

On MacOS/iOS:

 ERROR at //chrome/updater/mac/BUILD.gn:13:1: Value collision.
 import("//chrome/updater/branding.gni")
 ^-------------------------------------
 This import contains "keystone_app_name"
 See //brave/chromium_src/chrome/updater/branding.gni:18:23: defined here.
   keystone_app_name = "BraveSoftwareUpdate"
                       ^--------------------
 Which would clobber the one in your current scope
 See //chrome/enterprise_companion/branding.gni:32:23: defined here.
   keystone_app_name = "ChromiumSoftwareUpdate"
                       ^-----------------------
 Executing import should not conflict with anything in the current
 scope unless the values are identical.
 See //chrome/updater/BUILD.gn:23:14: which caused the file to be included.
     deps = [ "//chrome/updater/mac" ]
              ^---------------------

Chromium change:

https://source.chromium.org/chromium/chromium/src/+/bd96319778e6f280a4915b29f1ca16c16d6f00af

commit bd96319778e6f280a4915b29f1ca16c16d6f00af
Author: Noah Rose Ledesma <[email protected]>
Date:   Tue Aug 6 21:41:11 2024 +0000

    Create pkg installer for MacOS

    Add a build rule which creates a pkg installer for MacOS. The pkg
    installer copies the application bundle to a staging directory (adj. to
    the installation), and runs the enterprise_companion binary with the
    install flag, akin to O4's installer.

    Behind the install flag, the logic for Linux's installer is now shared
    with Mac to simply copy the executable to the install directory and
    configure permissions.

    Finally, a new integration test target was added to provide coverage of
    this installation experience. Integration tests are distinct from unit
    tests in that they will require root/admin privileges.

    Bug: 344878963

patches/chrome-enterprise_companion-branding.gni.patch

@@ -0,0 +1,9 @@
+diff --git a/chrome/enterprise_companion/branding.gni b/chrome/enterprise_companion/branding.gni
+index 3e626f26396e1f2bdf68b72b4f5b8563e0650caa..a7a951b2f765f89a5501991e89b77294ab0dc7d4 100644
+--- a/chrome/enterprise_companion/branding.gni
++++ b/chrome/enterprise_companion/branding.gni
+@@ -41,3 +41,4 @@ enterprise_companion_device_management_realtime_reporting_url =
+ enterprise_companion_device_management_encrypted_reporting_url =
+     "https://chromereporting-pa.googleapis.com/v1/record"
+ enterprise_companion_event_logging_url = "https://play.googleapis.com/log"
++import("//brave/chromium_src/chrome/updater/branding.gni") forward_variables_from(brave_updater_branding, ["keystone_app_name"])