[FIR] Refactor effective visibility calculation

Before this commit, we had effective visibility as a part of FIR status,
so it was integrated into the full pipeline. In this commit,
we introduced "effective visibility as a service" which is now used
only by exposed visibility checker. This allows us to make the thing
universal for all FIR nodes, including nodes for Java / deserialized.

compiler/testData/diagnostics/tests/exposed/protectedSameWay.fir.kt

@@ -1,13 +0,0 @@
-abstract class Outer {
-    protected open class My
-    // Both valid: same way protected
-    protected class Your: My()
-    abstract protected fun foo(my: My): Your
-}
-
-class OuterDerived: Outer() {
-    // valid, My has better visibility
-    protected class His: Outer.My()
-    // valid, My and Your have better visibility
-    override fun <!EXPOSED_FUNCTION_RETURN_TYPE!>foo<!>(<!EXPOSED_PARAMETER_TYPE!>my: Outer.My<!>) = Outer.Your()
-}

compiler/testData/diagnostics/tests/exposed/protectedSameWay.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 abstract class Outer {
     protected open class My
     // Both valid: same way protected