KT-18040: Enable auto popup when typing after $e. in string template

#KT-18040 fixed

idea/idea-completion/testData/confidence/AutoPopupInStringTemplate.kt

@@ -0,0 +1,10 @@
+class Bar {
+    val aa = "Some"
+}
+
+fun foo() {
+    val bar = Bar()
+    val y = "$bar.<caret>"
+}
+
+// ELEMENT: aa

idea/idea-completion/testData/confidence/NoAutoPopupInRawStringTemplateAfterNewLine.kt

@@ -0,0 +1,11 @@
+class Bar {
+    val aa = "Some"
+}
+
+fun foo() {
+    val bar = Bar()
+    val y = """$bar.
+a<caret>"""
+}
+
+// NO_LOOKUP

idea/idea-completion/testData/confidence/NoAutoPopupInString.kt

@@ -2,3 +2,4 @@ fun test() {
     "a<caret>"
 }
 
+// NO_LOOKUP

idea/idea-completion/testData/confidence/NoAutoPopupInStringTemplateAfterSpace.kt

@@ -0,0 +1,10 @@
+class Bar {
+    val aa = "Some"
+}
+
+fun foo() {
+    val bar = Bar()
+    val y = "$bar. a<caret>"
+}
+
+// NO_LOOKUP