[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/16.0/.prettierrc.yml

@@ -0,0 +1,8 @@
+# Defaults for all prettier-supported languages.
+# Prettier will complete this with settings from .editorconfig file.
+bracketSpacing: false
+printWidth: 88
+proseWrap: always
+semi: true
+trailingComma: "es5"
+xmlWhitespaceSensitivity: "strict"