Add support for a local file URI when adding a plugin to userPlugins

[SpiderUnderUrBed]

I get a error when i try:

 programs = {
    nixcord = {
      vesktop.enable = true;
      enable = true;
      userPlugins = {   
#       hideUsers = "github:SpiderUnderUrBed/hideUsers/7ab6d9d74d393b56684da7760fbe44e5684c1924";
        hideUsers = "/home/spiderunderurbed/projects/vesktop/hideUsers/output/userplugins/hideUser";
     };
      extraConfig = {
        plugins = {
        hideUsers.enable = true;
        };
      };

More specifically, I get a issue when I try to specify a directory instead of a URL for a plugin I'm developing.
This is the error I get:

       error: A definition for option `programs.nixcord.userPlugins.hideUsers' is not of type `(path in the Nix store or package convertible to it) or string matching the pattern github:([[:alnum:].-]+)/([[:alnum:]/-]+)/([0-9a-f]{40}) convertible to it'. Definition values:
       - In `/nix/store/xkfkixi04ah4vqsf3q30x4hm3szhi0cw-source/home.nix': "/home/spiderunderurbed/projects/vesktop/hideUsers/output/userplugins/hideUser"

Suggestion, add the ability to specify a local directory to be added to userPlugins