[DebugInfo] convert btf_tag attrs to annotations for DIComposite types

Clang patch D106614 added attribute btf_tag support. This patch
generates btf_tag annotations for DIComposite types.
Each btf_tag annotation is represented as a 2D array of
meta strings. Each record may have more than one
btf_tag annotations.

Differential Revision: https://reviews.llvm.org/D106615