[DebugInfo] generate btf_tag annotations for DIDerived types

Generate btf_tag annotations for DIDrived types. More specifically,
clang frontend generates the btf_tag annotations for record
fields. The annotations are represented as an DINodeArray
in DebugInfo. The following example illustrate how
annotations are encoded in IR:
      distinct !DIDerivedType(tag: DW_TAG_member, ..., annotations: !10)
      !10 = !{!11, !12}
      !11 = !{!"btf_tag", !"a"}
      !12 = !{!"btf_tag", !"b"}

Differential Revision: https://reviews.llvm.org/D106616

llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -1687,6 +1687,8 @@ void ModuleBitcodeWriter::writeDIDerivedType(const DIDerivedType *N,
   else
     Record.push_back(0);
 
+  Record.push_back(VE.getMetadataOrNullID(N->getAnnotations().get()));
+
   Stream.EmitRecord(bitc::METADATA_DERIVED_TYPE, Record, Abbrev);
   Record.clear();
 }