[red-knot] is_subtype_of: treat literals as subtype of 'object' (#13876)
Add the following subtype relations:
- `BooleanLiteral <: object`
- `IntLiteral <: object`
- `StringLiteral <: object`
- `LiteralString <: object`
- `BytesLiteral <: object`
Added a test case for `bool <: int`.
## Test Plan
New unit tests.