[FIR] Add UNCHECKED_CAST

Regenerate diagnostics code

compiler/fir/analysis-tests/testData/resolve/lambdaInLhsOfTypeOperatorCall.kt

@@ -5,11 +5,11 @@ fun foo(b: B<Int, Int>) {}
 fun test_1(b: B<String, Number>) {
     foo(b.myMap {
         it.k.length // implicits
-    } as B<Int, Int>)
+    } <!UNCHECKED_CAST!>as B<Int, Int><!>)
 }
 
 fun test_2(s: String) {
-    val func = { s.length } <!CAST_NEVER_SUCCEEDS!>as<!> B<Int, Int>
+    val func = { s.length } <!UNCHECKED_CAST!>as B<Int, Int><!>
 }
 
 class B<out K, V>(val k: K, val v: V)

compiler/fir/analysis-tests/testData/resolve/types/castToBareType.kt

@@ -12,6 +12,6 @@ interface AbstractFirBasedSymbol<E> where E : FirSymbolOwner<E>, E : FirDeclarat
 fun foo(firAdaptee: FirFunction<*>) {}
 
 fun test(symbol: AbstractFirBasedSymbol<*>) {
-    val firAdaptee = symbol.fir as FirFunction
+    val firAdaptee = symbol.fir <!UNCHECKED_CAST!>as FirFunction<!>  // TODO: KT-48832
     foo(firAdaptee)
 }