[libObject,llvm-readelf] - Stop describing a section/segment in `notes_begin()`.

`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:
(See D92021).

```
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.

Differential revision: https://reviews.llvm.org/D92081