support rulesets and config file

Support config files located at:
- $SYSTEM/mxlint.yaml
- $PROJECT/mxlint.yaml

project has higher precedence than system.

Structure:
```yaml
rulesets:
  - file://rules
  - https://example.com/rules.zip
  - git://github.com/mxlint/mxlint-rules
 rulesPath: .mendix-cache/rules
lint:
  skip:
    example/doc:
    - rule: 001_002
      reason: some reason
      date: 2026-02-27 11:00:00Z

```