[FIR] Add ReturnsImplies effect analyzer

compiler/tests-spec/testData/diagnostics/notLinked/contracts/declarations/contractBuilder/common/pos/1.fir.kt

@@ -0,0 +1,32 @@
+// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
+
+
+import kotlin.contracts.*
+
+// TESTCASE NUMBER: 1
+inline fun case_1(block: () -> Unit) {
+    contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) }
+    return block()
+}
+
+// TESTCASE NUMBER: 2
+inline fun case_2(value_1: Int?, block: () -> Unit): Boolean {
+    contract {
+        callsInPlace(block, InvocationKind.EXACTLY_ONCE)
+        returns(true) implies (value_1 != null)
+    }
+    block()
+    return value_1 != null
+}
+
+// TESTCASE NUMBER: 3
+inline fun <T> T?.case_3(value_1: Int?, value_2: Boolean, value_3: Int?, block: () -> Unit): Boolean? {
+    <!WRONG_IMPLIES_CONDITION!>contract {
+        callsInPlace(block, InvocationKind.EXACTLY_ONCE)
+        returns(true) implies (value_1 != null)
+        returns(false) implies (!value_2)
+        returnsNotNull() implies (this@case_3 != null && value_3 != null)
+    }<!>
+    block()
+    return value_1 != null
+}

compiler/tests-spec/testData/diagnostics/notLinked/contracts/declarations/contractBuilder/common/pos/1.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
 
 /*