refactor: combine `Expr::Like` and `Expr::ILike`

[waynexia]

Is your feature request related to a problem or challenge?

Expr::Like and Expr::ILike are based on the same Like struct. And most of their logic is similar.

Describe the solution you'd like

Combine Expr::Like and Expr::ILike variants. And express the I by adding one field ignore_case: bool in the Like struct

Describe alternatives you've considered

Keep it as is

Additional context

#6840 Has to handle two similar cases from Like and ILike.