[FIR] Properly track problems in contract description during effect extraction

compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/emptyContract.fir.kt

@@ -5,5 +5,5 @@
 import kotlin.contracts.*
 
 fun emptyContract() {
-    contract { }
-}
+    <!ERROR_IN_CONTRACT_DESCRIPTION!>contract { }<!>
+}

compiler/testData/diagnostics/testsWithStdLib/contracts/dsl/errors/illegalConstructionInContractBlock.fir.kt

@@ -25,9 +25,9 @@ fun whenInContract(x: Any?, boolean: Boolean) {
 
 fun forInContract(x: Any?) {
     contract {
-        for (i in 0..1) {
+        <!ERROR_IN_CONTRACT_DESCRIPTION!>for (i in 0..1) {
             returns() implies (x is String)
-        }
+        }<!>
     }
 }