Previously, when no file annotations were present, the FIR element
didn't have a source.
By making it nullable, it will only be created when appropriate and the
source will never be null.
#KT-55835
Now we will try to avoid redundant calculation:
* Class-like declarations can be calculated without super types
* Overridden search logic not is out of lock
Unfortunately, right now it is not safe to use
StatusResolveMode.FunctionWithSpecificName and
StatusResolveMode.PropertyWithSpecificName
because lazyResolveToPhaseWithCallableMembers can lead to an incorrect
state of scope. Example:
```
open class A {
open fun a() {}
open fun b() {}
}
class C : A()
```
Steps:
1. Resolve constructor of C to STATUS
2. Now we want to call lazyResolveToPhaseWithCallableMembers on
C, and this call will do nothing because this class and all
its declarations (only constructor) are already in STATUS phase,
so class A won't be resolved as expected
^KT-56551
Kirill Rakhman