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.

tests/sqlite.ini.tmpl

@@ -114,7 +114,7 @@ ENABLED = true
 [markup.html]
 ENABLED = true
 FILE_EXTENSIONS = .html
-RENDER_COMMAND = go run build/test-echo.go
+RENDER_COMMAND = go run tools/test-echo.go
 ;RENDER_COMMAND = cat
 ;IS_INPUT_FILE = true
 RENDER_CONTENT_MODE = sanitized