nixos/tsm-client: init module

This commit brings a module that installs the
IBM Spectrum Protect (Tivoli Storage Manager)
command-line client together with its
system-wide client system-options file `dsm.sys`.

nixos/modules/module-list.nix

@@ -138,6 +138,7 @@
   ./programs/sway.nix
   ./programs/thefuck.nix
   ./programs/tmux.nix
+  ./programs/tsm-client.nix
   ./programs/udevil.nix
   ./programs/venus.nix
   ./programs/vim.nix