monarch generator does not handle case insensitivity and does not escape "\"

[dhrubomoy]

Langium version: 4.0.0
Package name: langium-cli

Steps To Reproduce

1. Make sure the grammar has "\"
2. In language config add "monarch" prop so that it generates monarch rules

"monarch": {
    "out": "syntaxes/mylang.monarch.ts"
}

3. Add "caseInsensitive": true
4. Run npm run langium:generate.

Link to code example: N/A

The current behavior

In the generated .ts file it does not include ignoreCase: true and does not escape '\'

The expected behavior

Should include ignoreCase: true and escape '\\'