Support multiple variant for generate_from_impl_for_enum

[A4-Tacks]

Close #17493

Example

enum A { $0Foo(u32), Bar$0(i32) }

Before this PR

enum A { Foo(u32), Bar(i32) }

impl From<u32> for A {
    fn from(v: u32) -> Self {
        Self::Foo(v)
    }
}

After this PR

enum A { Foo(u32), Bar(i32) }

impl From<u32> for A {
    fn from(v: u32) -> Self {
        Self::Foo(v)
    }
}

impl From<i32> for A {
    fn from(v: i32) -> Self {
        Self::Bar(v)
    }
}