FIR: don't count implicit built-in type as a kind of implicit type

Before this commit, implicit Unit type for function with body and
without type, implicit Boolean type for conditions etc. were 'implicit'
types and resolved types together.
Sometimes this could lead to hard-to-find issues in FIR resolve, because
'implicit' types are usually handled there as 'necessary to resolve'
which is wrong for such effectively-resolved types.

compiler/fir/tree/src/org/jetbrains/kotlin/fir/FirRenderer.kt

@@ -710,7 +710,7 @@ class FirRenderer(builder: StringBuilder) : FirVisitorVoid() {
     }
 
     override fun visitImplicitTypeRef(implicitTypeRef: FirImplicitTypeRef) {
-        print(if (implicitTypeRef is FirImplicitBuiltinTypeRef) "${implicitTypeRef.id}" else "<implicit>")
+        print("<implicit>")
     }
 
     override fun visitTypeRefWithNullability(typeRefWithNullability: FirTypeRefWithNullability) {
@@ -740,10 +740,14 @@ class FirRenderer(builder: StringBuilder) : FirVisitorVoid() {
 
     override fun visitResolvedTypeRef(resolvedTypeRef: FirResolvedTypeRef) {
         resolvedTypeRef.annotations.renderAnnotations()
-        print("R|")
+        if (resolvedTypeRef !is FirImplicitBuiltinTypeRef) {
+            print("R|")
+        }
         val coneType = resolvedTypeRef.type
         print(coneType.render())
-        print("|")
+        if (resolvedTypeRef !is FirImplicitBuiltinTypeRef) {
+            print("|")
+        }
         if (coneType !is ConeKotlinErrorType && coneType !is ConeClassErrorType) {
             print(coneType.nullability.suffix)
         }

compiler/fir/tree/src/org/jetbrains/kotlin/fir/types/impl/FirImplicitBuiltinTypeRef.kt

@@ -11,23 +11,18 @@ import org.jetbrains.kotlin.fir.expressions.FirAnnotationCall
 import org.jetbrains.kotlin.fir.symbols.ConeClassLikeLookupTagImpl
 import org.jetbrains.kotlin.fir.symbols.StandardClassIds
 import org.jetbrains.kotlin.fir.types.ConeKotlinType
-import org.jetbrains.kotlin.fir.types.FirImplicitTypeRef
 import org.jetbrains.kotlin.fir.types.FirResolvedTypeRef
-import org.jetbrains.kotlin.fir.visitors.FirVisitor
 import org.jetbrains.kotlin.name.ClassId
 
 sealed class FirImplicitBuiltinTypeRef(
     override val session: FirSession,
     override val psi: PsiElement?,
     val id: ClassId
-) : FirImplicitTypeRef, FirResolvedTypeRef {
+) : FirResolvedTypeRef {
     override val annotations: List<FirAnnotationCall>
         get() = emptyList()
 
     override val type: ConeKotlinType = ConeClassTypeImpl(ConeClassLikeLookupTagImpl(id), emptyArray(), false)
-
-    override fun <R, D> accept(visitor: FirVisitor<R, D>, data: D): R =
-        visitor.visitImplicitTypeRef(this, data)
 }
 
 class FirImplicitUnitTypeRef(