[BOLT] Use symbol table info in registerFragment (#89648)

Fragment matching relies on symbol names to identify and register split
function fragments. However, as split fragments are often local symbols,
name aliasing is possible. For such cases, use symbol table to resolve
ambiguities.

This requires the presence of FILE symbols in the input binary. As BOLT
requires non-stripped binary, this is a reasonable assumption. Note that
`strip -g` removes FILE symbols by default, but `--keep-file-symbols`
can be used to preserve them.

Depends on: https://github.com/llvm/llvm-project/pull/89861

Test Plan:
Updated X86/fragment-lite.s