[FIR] Move FirReturnsImpliesAnalyzer to the extended checkers

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/contractsOnMembers.fir.kt

@@ -17,7 +17,7 @@ open class Foo {
     }
 
     inline fun <reified T> assertIs(value: Any) {
-        <!WRONG_IMPLIES_CONDITION!>contract { returns() implies (value is T) }<!>
+        contract { returns() implies (value is T) }
     }
 }
 

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/nullabilitySmartcastWhenNullability.fir.kt

@@ -31,9 +31,9 @@ fun testNullWhenNull(x: Int?) {
 
 // NB. it is the same function as `nullWhenNull`, but annotations specifies other facet of the function behaviour
 fun notNullWhenNotNull (x: Int?): Int? {
-    <!WRONG_IMPLIES_CONDITION!>contract {
+    contract {
         returns(null) implies (x == null)
-    }<!>
+    }
     return x?.inc()
 }
 

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/equalsWithNullableBoolean.fir.kt

@@ -5,9 +5,9 @@
 import kotlin.contracts.*
 
 fun safeIsString(x: Any?): Boolean? {
-    <!WRONG_IMPLIES_CONDITION!>contract {
+    contract {
         returns(true) implies (x is String)
-    }<!>
+    }
     return x?.let { it is String }
 }
 

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withSubjectNullableBoolean.fir.kt

@@ -5,9 +5,9 @@
 import kotlin.contracts.*
 
 fun safeIsString(x: Any?): Boolean? {
-    <!WRONG_IMPLIES_CONDITION!>contract {
+    contract {
         returns(true) implies (x is String)
-    }<!>
+    }
     return x?.let { it is String }
 }