Can't find data directory when installed by luarocks

[shahms]

This might be a case of my holding it wrong, but when plenary.nvim is specified as a dependency in a rockspec file and installed and run via luarocks, the base and builtin filetypes aren't installed because the luarocks install dir isn't added to Nvim's runtimepath. When installed via one of the many plugin managers from within neovim, this works fine, but makes filetype support unreliable when invoked via luarocks test.