Added null-ls and mason-null-ls

lua/plugins/mason-null-ls.lua

@@ -0,0 +1,15 @@
+-- https://github.com/jay-babu/mason-null-ls.nvim
+
+return {
+    "jay-babu/mason-null-ls.nvim",
+    event = { "BufReadPre", "BufNewFile" },
+    dependencies = {
+        "williamboman/mason.nvim",
+        "jose-elias-alvarez/null-ls.nvim",
+    },
+    config = function()
+        require("mason-null-ls").setup {
+            automatic_setup = true,
+        }
+    end
+}

lua/plugins/null-ls.lua

@@ -0,0 +1,5 @@
+-- https://github.com/jose-elias-alvarez/null-ls.nvim
+
+return {
+    "jose-elias-alvarez/null-ls.nvim"
+}