Proto changes required to recognize external artifacts

--
MOS_MIGRATED_REVID=140769347

src/main/protobuf/intellij_ide_info.proto

diff --git a/src/main/protobuf/intellij_ide_info.proto b/src/main/protobuf/intellij_ide_info.proto
index 62979e3..2063347 100644
--- a/src/main/protobuf/intellij_ide_info.proto
+++ b/src/main/protobuf/intellij_ide_info.proto
@@ -25,6 +25,8 @@
 
   // set for derived artifacts (is_source = false)
   string root_execution_path_fragment = 4;
+  // whether this artifact comes from an external repository (bazel only)
+  bool is_external = 5;
 }
 
 message LibraryArtifact {