Generate CHECKCAST after ACONST_NULL in coroutines

If we do not do this, the state-machine builder will not know the type
of the ACONST_NULL, defaulting to Object, leading to VerifyError.
Alternatively, we could use LVT to deduce the type, but getting types
from LVT is something I got rid of long time ago, and I have no desire
to return it back.

Generating CHECKCAST hints the state-machine builder the type of the
variable avoiding the issue of VerifyError. However, this CHECKCAST
replaces StrictBasicValue.NULL_VALUE with BasicValue in
OptimizationBasicInterpreter. To preserve optimization on not-spilling
known nulls, introduce BasicValues, which represent typed nulls and
create BasicInterpreter, which is aware of them. This way we have the
best of two worlds - we do not spill known nulls, and we know the type
of ACONST_NULL.

 #KT-51718 Fixed

compiler/testData/codegen/bytecodeText/coroutines/cleanup/nullCleanup.kt

@@ -14,10 +14,5 @@ suspend fun test() {
 
 // 2 PUTFIELD .*L\$0 : Ljava/lang/Object;
 
-// JVM_TEMPLATES:
-// just before suspension point
-// 1 ACONST_NULL
-
-// JVM_IR_TEMPLATES:
 // two stores to initialize the `a` variable and one null constant to store in the spill slot.
 // 3 ACONST_NULL