[codec importance] Add aconfig feature flags

Test: Manual:
 - Test flag can be called in both codec frameworks (C++)
   and CTS (java)
 - Test flag can be flipped by tooling
  - adb shell device_config put codec_fwk\
      com.android.media.codec.flags.codec_importance true

Bug: 297929011
Change-Id: Iedf841d726ec596cca62fd446ffcd2b2185c6d07
diff --git a/media/aconfig/mediacodec_flags.aconfig b/media/aconfig/mediacodec_flags.aconfig
index 67ba3e5..90ddf27 100644
--- a/media/aconfig/mediacodec_flags.aconfig
+++ b/media/aconfig/mediacodec_flags.aconfig
@@ -6,3 +6,10 @@
   description: "Feature flags for large audio frame support"
   bug: "297219557"
 }
+
+flag {
+  name: "codec_importance"
+  namespace: "codec_fwk"
+  description: "Feature flags for media codec importance"
+  bug: "297929011"
+}