[foundation] instruction parameter naming and access

[toth-istvan-zoltan]

Currently the instructions() function can be used to access instructions inside the fragment:

@Adaptive
fun a(hover : Boolean, instructions : AdaptiveInstructionGroup, @Adaptive b : () -> Unit) {
    if (hover) {
        box(instructions()) {
            b()
        }
    }
}

However, this is inconvenient as the parameter name is also instructions and import of the function cannot be done easily because of this.