Install language server(s)

[cceckman]

gopls for go: https://github.com/golang/go/wiki/gopls
clangd for C++: https://reviews.llvm.org/diffusion/L/browse/clang-tools-extra/trunk/clangd/

Kythe also provides an LSP, but it may not be as complete as language-specific ones: https://github.com/kythe/kythe/blob/master/README.langserver.md

[cceckman]

This may require (or may only be useful with) YouCompleteMe turned on.