Remove default predicate for `cols {}` in Selection DSL

[Jolanrensen]

In the selection dsl you can write:
myGroup.cols() if you want to refer to all columns nested inside the group.
This is allowed, because the default argument makes it myGroup.cols { true }.

However, because we use a predicate, we cannot get compiler plugin support for that function.
It's better to let users use all() and allCols() instead. It's more expressive and can get compiler plugin backing :)

We need to simply create overloads for cols() without argument, deprecate them and point people to the all() family.