Implement IdeReplCompletionTest to test completion of entities declared in already evaluated lines

idea/testData/repl/completion/builtInMember.kt

@@ -0,0 +1,4 @@
+>> val c = 4
+-- c.unary
+// EXIST: unaryPlus
+// EXIST: unaryMinus

idea/testData/repl/completion/definedClass.kt

@@ -0,0 +1,4 @@
+>> class MyClass { fun f() {} fun g() {} }
+-- val g: M
+// EXIST: MyClass
+

idea/testData/repl/completion/definedClassMember.kt

@@ -0,0 +1,5 @@
+>> class MyClass { fun f() {} fun g() {} }
+-- MyClass().
+// EXIST: f
+// EXIST: g
+

idea/testData/repl/completion/definedExtension.kt

@@ -0,0 +1,4 @@
+>> fun String.myExt() = "a"
+-- "asd".myEx
+// EXIST: myExt
+// NOTHING_ELSE

idea/testData/repl/completion/functions.kt

@@ -0,0 +1,8 @@
+>> fun foo() {}
+>> fun foo(i: Int) {}
+>> fun foo(s: String = "asd") {}
+>> foo(3)
+-- fo
+// EXIST: { itemText: "foo", tailText:"()" }
+// EXIST: { itemText: "foo", tailText:"(i: Int)" }
+// EXIST: { itemText: "foo", tailText:"(s: String = ...)" }

idea/testData/repl/completion/stdlib.kt

@@ -0,0 +1,3 @@
+>> val str = "a"
+-- str.capi
+// EXIST: capitalize

idea/testData/repl/completion/variables.kt

@@ -0,0 +1,5 @@
+>> var variable = 5
+>> var variable2 = "Sdsd"
+-- varia
+// EXIST: variable
+// EXIST: variable2