Reapply "Import Dexter to debuginfo-tests""

This reverts commit cb935f345683194e42e6e883d79c5a16479acd74.

Discussion in D68708 advises that green dragon is being briskly
refurbished, and it's good to have this patch up testing it.

GitOrigin-RevId: 984fad243d179564df31c5f9531a52442e24581a
169 files changed