Add Bindings for `Expr::Alias`

**Is your feature request related to a problem or challenge? Please describe what you are trying to do.**
Add Bindings for `Expr::Alias` in the Python `expr` module

**Describe the solution you'd like**
Introduce new `alias.rs` file in the Python `expr` module that provides bindings for the Datafusion code.

**Describe alternatives you've considered**
None

**Additional context**
None
