KT-4519 Show first line with content of block comment when collapsed (#928)

idea/testData/folding/noCollapse/kdocComments.kt

@@ -1,9 +1,9 @@
-<fold text='/**...*/'>/**
+<fold text='/** Kdoc licence ...*/'>/**
  * Kdoc licence
  */</fold>
 package some
 
-<fold text='/**...*/'>/**
+<fold text='/** Some Kdoc comment ...*/'>/**
  * Some Kdoc comment
  */</fold>
 class A

idea/testData/folding/noCollapse/multilineComments.kt

@@ -1,4 +1,5 @@
-<fold text='/.../'>/*
+<fold text='/ Some multiline comment .../'>/*
  * Some multiline comment
+ * And more comment
  */</fold>
 class A