introduce: shrink selection to exclude whitespaces and comments (IDEA-149120)

java/java-tests/testData/refactoring/introduceVariable/SubexpressionWithSpacesInSelectionAndTailingComment.after.java

@@ -0,0 +1,8 @@
+class Test {
+  {
+      final String ab = "".substring(1)
+              .substring(1);
+      ab // comment
+      .notify()
+  }
+}

java/java-tests/testData/refactoring/introduceVariable/SubexpressionWithSpacesInSelectionAndTailingComment.java

@@ -0,0 +1,7 @@
+class Test {
+  {
+<selection>    "".substring(1)
+      .substring(1) // comment</selection>
+      .notify()
+  }
+}