[FIR] Support completion of lambdas with type variable as expected type

#KT-37310 Fixed
#KT-37304 Fixed

compiler/testData/codegen/box/regressions/functionLiteralAsLastExpressionInBlock.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 fun box(): String {
     val p: (String) -> Boolean = if (true) {
         { true }

compiler/testData/codegen/box/regressions/lambdaAsLastExpressionInLambda.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 val foo: ((String) -> String) = run {
     { it }
 }