plugins/jj-nvim: rename -> jj

https://github.com/nix-community/nixvim/pull/4290#issuecomment-4455883922

plugins/by-name/jj/default.nix

@@ -1,6 +1,6 @@
 { lib, ... }:
 lib.nixvim.plugins.mkNeovimPlugin {
-  name = "jj-nvim";
+  name = "jj";
   moduleName = "jj";
   package = "jj-nvim";
   description = "Drive Jujutsu (jj) VCS from Neovim like a pro";

tests/test-sources/plugins/by-name/jj/default.nix

@@ -1,13 +1,13 @@
 {
   empty = {
-    plugins.jj-nvim.enable = true;
+    plugins.jj.enable = true;
   };
 
   example = {
     plugins.snacks.enable = true;
     plugins.codediff.enable = true;
 
-    plugins.jj-nvim = {
+    plugins.jj = {
       enable = true;
 
       settings = {
@@ -20,7 +20,7 @@
   };
 
   no-packages = {
-    plugins.jj-nvim.enable = true;
+    plugins.jj.enable = true;
     dependencies.jujutsu.enable = false;
   };
 }