Better caret position after Insert curly braces around variable (KT-28739)

Introduce helper class and move caret to it's original position.

 #KT-28739 Fixed

idea/testData/intentions/insertCurlyBracesToTemplate/insertBrackets1.kt.after

@@ -1,5 +1,5 @@
 // IS_APPLICABLE: true
 fun foo() {
     val x = 4
-    val y = "${x}"
+    val y = "${<caret>x}"
 }

idea/testData/intentions/insertCurlyBracesToTemplate/insertBrackets2.kt.after

@@ -1,5 +1,5 @@
 // IS_APPLICABLE: true
 fun foo() {
     val x = 4
-    val y = "something${x}.somethingelse"
+    val y = "something${<caret>x}.somethingelse"
 }

idea/testData/intentions/insertCurlyBracesToTemplate/insertBrackets4.kt.after

@@ -1,5 +1,5 @@
 // IS_APPLICABLE: true
 fun foo() {
     val x = 4
-    val y = "$x${x}$x"
+    val y = "$x${<caret>x}$x"
 }

idea/testData/intentions/insertCurlyBracesToTemplate/insertBrackets5.kt.after

@@ -1,5 +1,5 @@
 // IS_APPLICABLE: true
 fun foo() {
     val x = 4
-    val y = """$x${x}$x"""
+    val y = """$x${<caret>x}$x"""
 }

idea/testData/intentions/insertCurlyBracesToTemplate/insertBracketsEnd.kt

@@ -0,0 +1,2 @@
+val test = "some"
+val other = "text $test<caret> text"

idea/testData/intentions/insertCurlyBracesToTemplate/insertBracketsEnd.kt.after

@@ -0,0 +1,2 @@
+val test = "some"
+val other = "text ${test<caret>} text"

idea/testData/intentions/insertCurlyBracesToTemplate/insertBracketsMiddle.kt

@@ -0,0 +1,2 @@
+val test = "some"
+val other = "text $te<caret>st text"

idea/testData/intentions/insertCurlyBracesToTemplate/insertBracketsMiddle.kt.after

@@ -0,0 +1,2 @@
+val test = "some"
+val other = "text ${te<caret>st} text"