Add golangci-lint for golang linting

lua/null-ls/builtins/diagnostics.lua

@@ -841,4 +841,42 @@ M.qmllint = h.make_builtin({
     factory = h.generator_factory,
 })
 
+M.golangci_lint = h.make_builtin({
+    method = DIAGNOSTICS,
+    filetypes = { "go" },
+    generator_opts = {
+        command = "golangci-lint",
+        to_stdin = true,
+        from_stderr = false,
+        args = {
+            "run",
+            "--fast",
+            "--out-format",
+            "json",
+            "$DIRNAME",
+            "--path-prefix",
+            "$ROOT",
+        },
+        format = "json",
+        check_exit_code = function(code)
+            return code <= 2
+        end,
+        on_output = function(params)
+            local diags = {}
+            for _, d in ipairs(params.output.Issues) do
+                print(d.Pos.Filename)
+                if d.Pos.Filename == params.bufname then
+                    table.insert(diags, {
+                        row = d.Pos.Line,
+                        col = d.Pos.Column,
+                        message = d.Text,
+                    })
+                end
+            end
+            return diags
+        end,
+    },
+    factory = h.generator_factory,
+})
+
 return M