FIR translates:
```
when (x) {
1, 2, 3 -> action
else -> other_action
}
```
to an IR structure with nested ors:
```
if ((x == 1 || x == 2) || (x == 3)) action
else other_action
```
This change allows that to turn into switch instructions in the
JVM backend.
It's not correct to expect that the backend generates the `when` in this
test as tableswitch because there are only two branches. JVM IR has a
cutoff in the when optimization and generates `when`s with fewer than 3
branches as if-else chains, which is probably better. Note that there's
also a corresponding box test in when/enumOptimization/, so the backend
behavior is still tested.
This gives us more precise type information and can enable backend
optimizations. This was motivated by when expressions not compiled
to table switches in the JVM_IR backend.
Fixed KT-36845.
Otherwise some tools break (e.g. CheckMethodAdapter in ASM, used in generic
signature writer) because they expect class names to be Java identifiers.
Some tests fixed, some will be fixed in future commits
Dmitry Petrov