Motivation for this change

In response to #76184.

Things done

Type-infer the options, trying to be most reasonable.
enable is treated as a boolean in the code.
server has to be a string and it doesn't make sense to merge multiple values.
config is text. Oddly enough the existing code causes a merge with any user-selected value under the deprecated types.string rules. I decided types.lines was a safe enough replacement since blank lines aren't significant in the tsocks.conf format.

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests) don't think there are any
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip" inapplicable
• Tested execution of all binary files (usually in ./result/bin/) inapplicable
• Determined the impact on package closure size (by running nix path-info -S before and after) inapplicable
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Notify maintainers

unclear: Module is deprecated and abandonned.