Also accept alignment from if keyword in genKeepIdentIfThenElse.

[nojaf]

See #2973.

@Smaug123 your desired result doesn't have a blank line after else:

module Program =
    let main _ =
        if false then
            1
        else
        printfn "hi!"
        0

We currently always add a blank line there. Do you want to change that behaviour as well?

[Smaug123]

I'm very happy with adding the blank line. I was toying with the question; without the blank line it does look a bit cramped.

[Smaug123]

I can't speak for the implementation, but the tests look like they're doing the right thing to me! Thanks.