[NI] Implement algorithm for completion mode selection

Current selection of completion mode for call is not always correct in case of full mode,
and sometimes too conservative in case of partial mode. Updated algorithm checks constraints
wrt position of type variables in return type and in other related constraints.
Full completion happens if proper constraint requirements are satisfied for variables.

compiler/testData/diagnostics/tests/inference/completion/basic.kt

@@ -0,0 +1,70 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_PARAMETER
+
+interface Bound
+class Cls : Bound
+
+class Inv<T>(val prop: T)
+class In<in I>(param: I)
+class InB<in I : Bound>(param: I)
+class Out<out O>(val prop: O)
+
+fun <K> id(arg: K): K = arg
+fun <W> makeInv(arg: W): Inv<W> = TODO()
+fun <O> wrapOut(arg: O): Inv<out O> = TODO()
+fun <I> wrapIn(arg: I): Inv<in I> = TODO()
+
+fun test1(cls: Cls) {
+    id(
+        <!DEBUG_INFO_EXPRESSION_TYPE("Inv<Cls>")!>Inv(cls)<!>
+    )
+}
+
+fun test2(cls: Cls) {
+    id<Inv<Bound>>(
+        <!DEBUG_INFO_EXPRESSION_TYPE("Inv<Bound>")!>Inv(cls)<!>
+    )
+}
+
+fun test3(cls: Cls) {
+    id<Out<Bound>>(
+        <!DEBUG_INFO_EXPRESSION_TYPE("Out<Cls>")!>Out(cls)<!>
+    )
+}
+
+fun test4(cls: Cls) {
+    id(
+        <!DEBUG_INFO_EXPRESSION_TYPE("Out<Cls>")!>Out(cls)<!>
+    )
+}
+
+fun test5(cls: Cls) {
+    id(
+        <!DEBUG_INFO_EXPRESSION_TYPE("In<Cls>")!>In(cls)<!>
+    )
+}
+
+fun test6(cls: Cls) {
+    id<In<Bound>>(
+        <!DEBUG_INFO_EXPRESSION_TYPE("In<Bound>")!>In(cls)<!>
+    )
+}
+
+fun test7(cls: Cls) {
+    id(
+        <!DEBUG_INFO_EXPRESSION_TYPE("Inv<out Cls>")!>wrapOut(cls)<!>
+    )
+}
+
+fun test8(cls: Cls) {
+    // TODO
+    <!IMPLICIT_NOTHING_AS_TYPE_PARAMETER, TYPE_MISMATCH!>id<!>(
+        <!DEBUG_INFO_EXPRESSION_TYPE("Inv<in Cls>")!>wrapIn(cls)<!>
+    )
+}
+
+fun test9(cls: Cls) {
+    id(
+        <!DEBUG_INFO_EXPRESSION_TYPE("InB<Bound>")!>InB(cls)<!>
+    )
+}