[Debuginfod] [Symbolizer] Break debuginfod out of libLLVM.

Debuginfod can pull in libcurl as a dependency, which isn't appropriate
for libLLVM. (See
https://gitlab.freedesktop.org/mesa/mesa/-/issues/5732).

This change breaks out debuginfod into a separate non-component library
that can be used directly in llvm-symbolizer. The tool can inject
debuginfod into the Symbolizer library via an abstract DebugInfoFetcher
interface, breaking the dependency of Symbolizer on debuinfod.

See https://github.com/llvm/llvm-project/issues/52731

Reviewed By: phosek

Differential Revision: https://reviews.llvm.org/D118413