Newline should be inserted before ?: in functional call chain

[petertrr]

Describe the bug

fun foo() {
    foo.bar().baz().qux() ?: baz
}

should be fixed to

fun foo() {
    foo
        .bar()
        .baz()
        .qux()
        ?: baz
}

but ?: isn't placed on a separate line

Environment information

• diktat version: 0.1.5

[orchestr7]

what to do with simple expressions?
I guess for simple expressions need to have it on the same line.

a ?: b

=>

is fine in both ways:
a ?: b
and

a 
    ?: b

because in some cases linelength rule can fix it

[petertrr]

I think rules should be the same as for usual calls chain:

• if right-hand side of ?: is a simple expression and left-hand side too, then they can be on the same line, but also can be split if the line is too long
• if RHS expression requires line breaks, ?: should start on a new line:

foo ?: bar.baz().qux()

should be

foo
    ?: bar
        .bar()
        .qux()

• if LHS already has line breaks, ?: should start on a new line

foo.bar()
    .baz()
    .qux()
    ?: boo