Migrate Android NDK to CIPD [1/2]

The Android NDK dependency is moving to a CIPD bucket to reduce the
checkout cost and to eventually move to NDK v25. This introduces the
NDK into an 'android_toolchain' directory. Following the roll of
chromium/base in this repository, a second change will delete the old
'android_ndk' checkout. As a result, the checkout size of this
repository will temporarily increase.

This change also updates the license generation scripts and build
helpers to ensure the android_toolchain is also accounted for.

Bug: chromium:1448383
Test: Verified local builds of WebRTC.
Change-Id: Ibe667be241e5a454d884482061dd10b9850be25f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/307540
Commit-Queue: Prashanth Swaminathan <prashanthsw@google.com>
Reviewed-by: Christoffer Jansson <jansson@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#40239}

DEPS

@@ -402,6 +402,17 @@ deps = {
       'condition': 'checkout_android',
   },
 
+  'src/third_party/android_toolchain': {
+    'packages': [
+      {
+        'package': 'chromium/third_party/android_toolchain/r23c/android_toolchain',
+        'version': 'version:2@r23c.cr0',
+      },
+    ],
+    'condition': 'checkout_android',
+    'dep_type': 'cipd',
+  },
+
   'src/third_party/androidx': {
     'packages': [
       {

tools_webrtc/libs/generate_licenses.py

@@ -36,6 +36,7 @@ LIB_TO_LICENSES_DICT = {
     'abseil-cpp': ['third_party/abseil-cpp/LICENSE'],
     'android_ndk': ['third_party/android_ndk/NOTICE'],
     'android_sdk': ['third_party/android_sdk/LICENSE'],
+    'android_toolchain': ['third_party/android_toolchain/NOTICE'],
     'auto': [
         'third_party/android_deps/libs/'
         'com_google_auto_service_auto_service/LICENSE'

tools_webrtc/presubmit_checks_lib/build_helpers.py

@@ -81,6 +81,7 @@ def RunNinjaCommand(args, root_dir=None):
 def GetClangTidyPath():
   """POC/WIP! Use the one we have, even it doesn't match clang's version."""
   tidy = ('third_party/android_ndk/toolchains/'
+          'third_party/android_toolchain/toolchains/'
           'llvm/prebuilt/linux-x86_64/bin/clang-tidy')
   return os.path.join(SRC_DIR, tidy)