[FIR] Introduce containsMultipleNonSubsumed to intersection overrides

After this change the IO created for
`SimpleColoredComponent::setToolTipText`
will be `containsMultipleNonSubsumed == true`
while IOs created for classes in
`intersectionOverridesIntersection.kt`
will have this property set to `false`.

^KT-65972 Fixed

compiler/fir/tree/src/org/jetbrains/kotlin/fir/symbols/impl/FirFunctionSymbol.kt

@@ -47,11 +47,19 @@ open class FirNamedFunctionSymbol(callableId: CallableId) : FirFunctionSymbol<Fi
 
 interface FirIntersectionCallableSymbol {
     val intersections: Collection<FirCallableSymbol<*>>
+
+    /**
+     * `true` iff a call to `nonSubsumed()` for `intersections` would result into a list with more than one symbol.
+     * Intuitively, `false` means this intersection is, strictly speaking, redundant, but we still created it
+     * as an implementation detail.
+     */
+    val containsMultipleNonSubsumed: Boolean
 }
 
 class FirIntersectionOverrideFunctionSymbol(
     callableId: CallableId,
     override val intersections: Collection<FirCallableSymbol<*>>,
+    override val containsMultipleNonSubsumed: Boolean,
 ) : FirNamedFunctionSymbol(callableId), FirIntersectionCallableSymbol
 
 class FirConstructorSymbol(callableId: CallableId) : FirFunctionSymbol<FirConstructor>(callableId), ConstructorSymbolMarker {

compiler/fir/tree/src/org/jetbrains/kotlin/fir/symbols/impl/FirVariableSymbol.kt

@@ -72,12 +72,14 @@ open class FirPropertySymbol(callableId: CallableId, ) : FirVariableSymbol<FirPr
 
 class FirIntersectionOverridePropertySymbol(
     callableId: CallableId,
-    override val intersections: Collection<FirCallableSymbol<*>>
+    override val intersections: Collection<FirCallableSymbol<*>>,
+    override val containsMultipleNonSubsumed: Boolean,
 ) : FirPropertySymbol(callableId), FirIntersectionCallableSymbol
 
 class FirIntersectionOverrideFieldSymbol(
     callableId: CallableId,
-    override val intersections: Collection<FirCallableSymbol<*>>
+    override val intersections: Collection<FirCallableSymbol<*>>,
+    override val containsMultipleNonSubsumed: Boolean,
 ) : FirFieldSymbol(callableId), FirIntersectionCallableSymbol
 
 class FirBackingFieldSymbol(callableId: CallableId) : FirVariableSymbol<FirBackingField>(callableId) {