Introduce `lazyval`

# WHY:

currently long boolean expressions cannot be organized and still benefit from lazy evaluation of boolean expressions

ex:

```
(heavyComputationFromASource1() && heavyComputationFromASource2()) || (heavyComputationFromBSource1() && heavyComputationFromBSource2()) || (heavyComputationFromCSource1() && heavyComputationFromCSource2())
```
is not equivalent to
```
val a = heavyComputationFromASource1() && heavyComputationFromASource2()
val b = heavyComputationFromBSource1() && heavyComputationFromBSource2()
val c = heavyComputationFromCSource1() && heavyComputationFromCSource2()

a || b || c
```

as at least `*Source1()` will be evaluated

# PROPOSAL:
With `lazyval` working under the hood as some kind of supplier code below would work and still benefit from lazy evaluation

```
lazyval a = heavyComputationFromASource1() && heavyComputationFromASource2()
lazyval b = heavyComputationFromBSource1() && heavyComputationFromBSource2()
lazyval c = heavyComputationFromCSource1() && heavyComputationFromCSource2()

a || b || c
```