[clangd] Cleanup dependencies around RemoteIndex

RemoteIndexClient implementations only depends on clangdSupport for
logging functionality and has no dependence on clangDeamon itself. This clears
out that link time dependency and enables depending on it in clangDeamon itself,
so that we can have other index implementations that makes use of the
RemoteIndex.

Differential Revision: https://reviews.llvm.org/D90746