[lld] [lld][WebAssembly] Match the ELF linker in transitioning away from archive indexes. (PR #78658)

[Fangrui Song via llvm-commits]

MaskRay wrote:

LGTM as well with a description clarification.

> This patch also removes `ArchiveFile`. The ELF reference probably should be [reviews.llvm.org/D119074](https://reviews.llvm.org/D119074) (`[ELF] Parse archives as --start-lib object files`).



https://github.com/llvm/llvm-project/pull/78658