notes_begin() is used for iterating over notes. This API in some cases might print
section type and index. At the same time during iterating, the Elf_Note_Iterator
might omit it as it doesn't have this info.
Because of above we might have the redundant duplication of information in warnings:
warning: '[[FILE]]': unable to read notes from the SHT_NOTE section with index 1: SHT_NOTE section [index 1] has invalid offset (0x40) or size (0xffff0000)
This change stops reporting section index/type in Object/ELF.h/notes_begin().
(FTR, this was introduced by me for llvm-readobj in D64470).
Instead we can describe sections/program headers on the caller side.