media: mechanism to set/get vendor-extension configs for OMX component

Add OMX_CONFIG_ANDROID_VENDOR_EXTENSIONTYPE and
OMX_CONFIG_ANDROID_VENDOR_PARAMTYPE.

Android vendor extensions for OMX components have a name and one or
more parameter values - each with a string key - that are set together.
Support for not-set values is provided for vendor extensions in order
to not suddenly confuse applications with format keys that they were
not expecting.

Bug: 32746650
Change-Id: I21aad4a82d509fe2466764f65ee9e3b2d32f0842
diff --git a/include/media/openmax/OMX_AsString.h b/include/media/openmax/OMX_AsString.h
index 4556c8f..6b21979 100644
--- a/include/media/openmax/OMX_AsString.h
+++ b/include/media/openmax/OMX_AsString.h
@@ -531,6 +531,7 @@
 //      case OMX_IndexConfigCallbackRequest:            return "ConfigCallbackRequest";
 //      case OMX_IndexConfigCommitMode:                 return "ConfigCommitMode";
 //      case OMX_IndexConfigCommit:                     return "ConfigCommit";
+        case OMX_IndexConfigAndroidVendorExtension:     return "ConfigAndroidVendorExtension";
         case OMX_IndexParamAudioAndroidAc3:             return "ParamAudioAndroidAc3";
         case OMX_IndexParamAudioAndroidOpus:            return "ParamAudioAndroidOpus";
         case OMX_IndexParamAudioAndroidAacPresentation: return "ParamAudioAndroidAacPresentation";