Misc tool tweaks (#35734)

Some minor tooling tweaks:

- Ignore .venv in golangci-lint
- Move go tools to tools directory (e.g. everything that is not "build")
- Enable reportUnusedInlineConfigs in eslint, no current violations
- Apply modernize fix in code-batch-process, modernize cli did
apparently not catch it because of the `go:build ignore` tag.

tools/test-echo.go

@@ -0,0 +1,20 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+//go:build ignore
+
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+func main() {
+	_, err := io.Copy(os.Stdout, os.Stdin)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error: %v", err)
+		os.Exit(1)
+	}
+}