Support generic type parameters in 'Specify return type explicitly'

So #KT-18074 Fixed

idea/testData/intentions/specifyTypeExplicitly/genericClass.kt

@@ -0,0 +1,5 @@
+fun <T> generic1(): T = null!!
+
+class My<T> {
+    fun <caret>foo() = generic1<T>()
+}

idea/testData/intentions/specifyTypeExplicitly/genericClass.kt.after

@@ -0,0 +1,5 @@
+fun <T> generic1(): T = null!!
+
+class My<T> {
+    fun foo(): T = generic1<T>()
+}

idea/testData/intentions/specifyTypeExplicitly/genericFunction.kt

@@ -0,0 +1,2 @@
+fun <T> generic1(): T? = null
+fun <T> <caret>foo() = generic1<T>()

idea/testData/intentions/specifyTypeExplicitly/genericFunction.kt.after

@@ -0,0 +1,2 @@
+fun <T> generic1(): T? = null
+fun <T> foo(): T? = generic1<T>()