Fix `cider-company-location`.

Much like #596; using `company-show-location` (bound to `C-w` when by default when completions are showing) was causing the location buffer to be displayed twice. 

This separates out the involved buffer creation logic so it can be used by `cider-company-location` without needing to call `cider-jump-to-def-for`, which pops the buffer up.