[FIR] Initialize public visibility for class-like declarations at FIR building phase if no modifier is presented

Java resolving subsystem requires calculated visibility for correct disambiguation of supertypes.
But visibility remains `Unknown` for Kotlin class-like declarations during supertypes resolving because `STATUS` resolve phase is performed after `SUPER_TYPES` phase.
To fix the problem, the visibility should be initialized to public at the FIR building phase if no modifier is presented.

^KT-64127 Fixed

analysis/low-level-api-fir/testData/getOrBuildFir/wholeDeclaration/function.txt

@@ -24,7 +24,7 @@ FILE: [ResolvedTo(IMPORTS)] function.kts
 
             public final [ResolvedTo(STATUS)] fun execute(): R|kotlin/Unit| { LAZY_BLOCK }
 
-            public? final? [ResolvedTo(RAW_FIR)] class NestedBuilder : Builder {
+            public final? [ResolvedTo(RAW_FIR)] class NestedBuilder : Builder {
                 public? [ResolvedTo(RAW_FIR)] [ContainingClassKey=NestedBuilder] constructor(): R|Builder.NestedBuilder| {
                     LAZY_super<Builder>
                 }