[ADD] support for Odoo 18.0 configuration

Add config/18.0/ with configuration files based on OCA standards:
- .pylintrc and .pylintrc-mandatory (valid-odoo-versions=18.0)
- .ruff.toml (Python linting)
- .pre-commit-config.yaml with updated hooks:
  - whool-init (new in 18.0)
  - oca-gen-external-dependencies (new in 18.0)
  - Updated prettier 3.x and eslint 9.x
- eslint.config.cjs and prettier.config.cjs (new flat config format)

Also move .eslintrc.yml and .prettierrc.yml to config/16.0/ since
18.0 uses the new CJS flat config format instead of YAML.

config/18.0/prettier.config.cjs

@@ -0,0 +1,14 @@
+/** @type {import('prettier').Config} */
+
+const config = {
+  // https://github.com/prettier/prettier/issues/15388#issuecomment-1717746872
+  plugins: [require.resolve("@prettier/plugin-xml")],
+  bracketSpacing: false,
+  printWidth: 88,
+  proseWrap: "always",
+  semi: true,
+  trailingComma: "es5",
+  xmlWhitespaceSensitivity: "preserve",
+};
+
+module.exports = config;