[FIR] Move FirReturnsImpliesAnalyzer to the extended checkers

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

@@ -1,39 +0,0 @@
-// !OPT_IN: kotlin.contracts.ExperimentalContracts
-
-/*
- * KOTLIN DIAGNOSTICS NOT LINKED SPEC TEST (POSITIVE)
- *
- * SECTIONS: contracts, declarations, contractBuilder, common
- * NUMBER: 1
- * DESCRIPTION: Functions with simple contracts.
- */
-
-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

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