[llvm-readelf] Print more information for RELR

llvm-readelf/llvm-readobj print RELR as REL relocations with a fixed
type (e.g. `R_*_RELATIVE`). GNU readelf printed only addresses and have
recently switched to a more descritive style that includes a symbolic
address column (symbolized using .symtab/.strtab) (milestone: binutils
2.43).

This patch implements the new GNU style, which seems superior to the
current REL style and essentially obsoletes LLVM-specific --raw-relr
(`printRelrReloc`).

Pull Request: https://github.com/llvm/llvm-project/pull/89162