add new rule: react-no-unnecessary-fragment

[tanmoyopenroot]

PR checklist

• Addresses an existing issue: fixes Rule suggestion: no unneeded <React.Fragment> or <> #198
• new rule
• Includes tests
• Documentation update

Overview of change:

Added react-no-unnecessary-fragment rule with some tests

{
    "rules": {
        "react-no-unnecessary-fragment": true
    }
}