Clangd as source of tags information.

[lvella]

The wonderful Vim plugin YouCompleteMe makes use of clangd to parse the currently open file and get the needed information to provide semantic auto-completion (initially it used its own server based on libclang to do it, but later version also supports clangd).

Since clangd already parses the file, and supposedly has all the information needed in order to generate tagbar's outline, it would be nice if instead of relying on exuberant ctag, it could fetch the information from the same clangd instance used by YouCompleteMe. Besides reusing parsing work, saving CPU cycles, it has the advantage of supporting the latest language standards supported by clang.