Select any SimpleExpr via QuerySelect

[billy1624]

Discussed on Discord: https://discord.com/channels/873880840487206962/1115651321995993128

Motivation

Now we cannot select SimpleExpr directly via QuerySelect interface.

let mut find = cake::Entity::find();

find.query()
    .expr(Expr::col(Alias::new("some_column")))
    .exprs([
        Expr::col(Alias::new("some_column")),
        Expr::col(Alias::new("some_column")),
    ])

Proposed Solutions

A new API can provide a shortcut for it.

cake::Entity::find()
    .expr(Expr::col(Alias::new("some_column")))
    .exprs([
        Expr::col(Alias::new("some_column")),
        Expr::col(Alias::new("some_column")),
    ])

[billy1624]

I will create a PR for this :)

[billy1624]

Closed by #1702