Effects: add diagnostic tests on contracts

- Make AbstractDiagnosticsTest dump function contracts
- Add diagnostics tests on parsing contracts
- Add diagnostics tests on smartcats in presence of functions with
contracts
- Add diagnostics tests on initialization and flow in presence of
in-place called lambdas

==========
Introduction of EffectSystem: 16/18

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/intersectingInfo.kt

@@ -0,0 +1,59 @@
+// !LANGUAGE: +ReturnsEffect
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.internal.contracts.*
+
+fun isString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+
+fun notIsString(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x is String)
+    }
+    return x !is String
+}
+
+fun notIsInt(x: Any?): Boolean {
+    contract {
+        returns(false) implies (x !is Int)
+    }
+    return x !is Int
+}
+
+fun intersectingInfo(x: Any?, y: Any?) {
+    if ((isString(x) && y is String) || (!notIsString(x) && !notIsInt(y))) {
+        <!DEBUG_INFO_SMARTCAST!>x<!>.length
+        y.<!UNRESOLVED_REFERENCE!>length<!>
+        y.<!UNRESOLVED_REFERENCE_WRONG_RECEIVER!>inc<!>()
+    }
+    else {
+        x.<!UNRESOLVED_REFERENCE!>length<!>
+        y.<!UNRESOLVED_REFERENCE!>length<!>
+        y.<!UNRESOLVED_REFERENCE_WRONG_RECEIVER!>inc<!>()
+    }
+}
+
+fun intersectingInfo2(x: Any?, y: Any?) {
+    // In each arg of "||"-operator presented fact "x is String" which should lead to smartcast.
+    // Also there are 3 additional facts: "x is Int", "y is String", "y is Int". One
+    // of them is absent in each arg of "||"-operator, so they *shouldn't* lead to smartcast
+
+    if ((isString(x) && !notIsInt(x) && y is String) ||
+        (!notIsString(x) && isString(y) && y is Int) ||
+        (x is String && !notIsInt(y) && x is Int)) {
+        <!DEBUG_INFO_SMARTCAST!>x<!>.length
+        x.<!UNRESOLVED_REFERENCE_WRONG_RECEIVER!>inc<!>()
+        y.<!UNRESOLVED_REFERENCE!>length<!>
+        y.<!UNRESOLVED_REFERENCE_WRONG_RECEIVER!>inc<!>()
+    }
+    x.<!UNRESOLVED_REFERENCE!>length<!>
+    x.<!UNRESOLVED_REFERENCE_WRONG_RECEIVER!>inc<!>()
+    y.<!UNRESOLVED_REFERENCE!>length<!>
+    y.<!UNRESOLVED_REFERENCE_WRONG_RECEIVER!>inc<!>()
+}
+