[FIR] Utilize equality compatibility logic for cast checks

This makes it more consistent and fixes some
overlooked corner cases. Also it was decided
on the last equality applicability DM
(KT-62646) that we'd like
`is`/`!is`/`as`/`as?` to work similarly
to `===`/`!==`.

Also note that it now gives a clearer
explaination of why some corner cases work
the way they do. For example,
`FirPsiDiagnosticTestGenerated.testLambdaInLhsOfTypeOperatorCall`
yields `UNCHECKED_CAST` instead of
`CAST_NEVER_SUCCEEDS`, because
`toTypeInfo()` replaces all type arguments
with star projections, even when the argument
is not a type parameter. This is because
it has been desided to work this way in
KT-57779.

In
`FirPsiOldFrontendDiagnosticsTestGenerated..NeverSucceeds#testNoGenericsRelated`
the diagnostic is introduced, because
`t2 as FC1` and `FC1` is a final class with
no `T5` supertype.

`UNCHECKED_CAST` in
`FirPsiOldFrontendDiagnosticsTestGenerated.testSmartCast`
disappeared, because previously we didn't
take smartcasts into account.

Note that
`FirPsiOldFrontendDiagnosticsTestGenerated.testMappedSubtypes`
is a false positive. It appears because `isSubtypeOf()` doesn't
take into account platform types in supertypes of the given types
(doesn't map them).

compiler/testData/diagnostics/tests/cast/IsErasedUpcastToNonReified.fir.kt

@@ -28,7 +28,7 @@ inline fun <reified T> test(x: T?, a: Any) {
     a is <!CANNOT_CHECK_FOR_ERASED!>Box<T><!>
     a is <!CANNOT_CHECK_FOR_ERASED!>Array<T><!>
     a <!UNCHECKED_CAST!>as Box<T><!>
-    a <!UNCHECKED_CAST!>as Array<T><!>
+    a <!CAST_NEVER_SUCCEEDS!>as<!> Array<T>
 
     a is <!CANNOT_CHECK_FOR_ERASED!>Box<List<T>><!>
     a is <!CANNOT_CHECK_FOR_ERASED!>Array<List<T>><!>

compiler/testData/diagnostics/tests/cast/neverSucceeds/MappedSubtypes.fir.kt

@@ -0,0 +1,21 @@
+// !DIAGNOSTICS: -PLATFORM_CLASS_MAPPED_TO_KOTLIN -UNUSED_PARAMETER -ABSTRACT_MEMBER_NOT_IMPLEMENTED -USELESS_CAST
+import java.lang.CharSequence as JCS
+
+class JSub: JCS
+class Sub: CharSequence
+
+fun test(
+  s: Sub,
+  js: JSub,
+  cs: CharSequence,
+  jcs: JCS
+) {
+  // js as CharSequence // - this case is not supported due to limitation in PlatformToKotlinClassMap
+  js <!CAST_NEVER_SUCCEEDS!>as<!> JCS
+
+  s as CharSequence
+  s as JCS
+
+  js <!CAST_NEVER_SUCCEEDS!>as<!> Sub
+  s <!CAST_NEVER_SUCCEEDS!>as<!> JSub
+}

compiler/testData/diagnostics/tests/cast/neverSucceeds/MappedSubtypes.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // !DIAGNOSTICS: -PLATFORM_CLASS_MAPPED_TO_KOTLIN -UNUSED_PARAMETER -ABSTRACT_MEMBER_NOT_IMPLEMENTED -USELESS_CAST
 import java.lang.CharSequence as JCS
 

compiler/testData/diagnostics/tests/cast/neverSucceeds/NoGenericsRelated.fir.kt

@@ -0,0 +1,46 @@
+// !DIAGNOSTICS: -USELESS_CAST -UNCHECKED_CAST
+interface T1
+interface T2
+interface T3
+open class OC1: T1
+open class OC2: OC1(), T2
+class FC1: OC2(), T3
+interface T4: <!INTERFACE_WITH_SUPERCLASS!>OC1<!>
+interface T5: T2
+
+fun <TP1: OC1, TP2: T2, TP3: OC2> test(
+    t2: T2,
+    t4: T4,
+    fc1: FC1,
+    oc1: OC1,
+    oc2: OC2,
+    tp1: TP1,
+    tp2: TP2
+) {
+  fc1 as FC1
+  fc1 as OC1
+  fc1 as T1
+  fc1 as TP1
+
+  oc1 as FC1
+  oc1 as OC2
+  oc2 as OC1
+  oc1 as T2
+  oc1 as T1
+  oc1 as TP1
+  oc1 as TP2
+
+  t2 as FC1
+  t2 as OC2
+  t4 as OC1
+  t2 as T2
+  t2 <!CAST_NEVER_SUCCEEDS!>as<!> T5
+  t2 as TP2
+
+  tp1 as FC1
+  tp1 as OC1
+  tp1 as OC2
+  tp2 as T2
+  tp2 as T5
+  tp1 as TP3
+}

compiler/testData/diagnostics/tests/cast/neverSucceeds/NoGenericsRelated.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // !DIAGNOSTICS: -USELESS_CAST -UNCHECKED_CAST
 interface T1
 interface T2

compiler/testData/diagnostics/tests/cast/neverSucceeds/NoGenericsUnrelated.fir.kt

@@ -0,0 +1,34 @@
+// !DIAGNOSTICS: -UNCHECKED_CAST
+interface Trait1
+interface Trait2
+open class OClass1
+open class OClass2
+class FClass1
+class FClass2
+
+fun <TP1: OClass1, TP2: OClass2> test(
+  t1: Trait1,
+  oc1: OClass1,
+  fc1: FClass1,
+  tp1: TP1
+) {
+  t1 as Trait2
+  t1 as OClass2
+  t1 <!CAST_NEVER_SUCCEEDS!>as<!> FClass2
+  t1 as TP2
+
+  oc1 as Trait2
+  oc1 as OClass2
+  oc1 <!CAST_NEVER_SUCCEEDS!>as<!> FClass2
+  oc1 as TP2
+
+  fc1 <!CAST_NEVER_SUCCEEDS!>as<!> Trait2
+  fc1 <!CAST_NEVER_SUCCEEDS!>as<!> OClass2
+  fc1 <!CAST_NEVER_SUCCEEDS!>as<!> FClass2
+  fc1 as TP2
+
+  tp1 as Trait2
+  tp1 as OClass2
+  tp1 <!CAST_NEVER_SUCCEEDS!>as<!> FClass2
+  tp1 as TP2
+}

compiler/testData/diagnostics/tests/cast/neverSucceeds/NoGenericsUnrelated.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // !DIAGNOSTICS: -UNCHECKED_CAST
 interface Trait1
 interface Trait2