Move test utilities into more specific build targets

Move audio- and video-specific utilities to audio_test_common (newly
added target) and video_test_common.

Bug: webrtc:10198
Change-Id: Ia10fa5c0a51d9b1f37db4964984d22fc5b269bb1
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/268980
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Auto-Submit: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37570}
diff --git a/modules/audio_coding/BUILD.gn b/modules/audio_coding/BUILD.gn
index fd1237b..556e68c 100644
--- a/modules/audio_coding/BUILD.gn
+++ b/modules/audio_coding/BUILD.gn
@@ -1557,7 +1557,7 @@
         ":neteq_test_tools",
         "../../api/audio_codecs:builtin_audio_decoder_factory",
         "../../api/neteq:neteq_api",
-        "../../test:audio_codec_mocks",
+        "../../test:audio_test_common",
         "../../test:field_trial",
         "../../test:test_support",
       ]
@@ -2111,6 +2111,7 @@
         "../../rtc_base/system:arch",
         "../../system_wrappers",
         "../../test:audio_codec_mocks",
+        "../../test:audio_test_common",
         "../../test:field_trial",
         "../../test:fileutils",
         "../../test:rtc_expect_death",