New enum syntax: Short constructor syntax introduced for entries, optional commas between entries, semicolon after entries. #KT-7605 Fixed.

Grammar changed accordingly.
Semicolons prohibited after an entry except the last one.
Only one initializer is allowed per entry.
EnumReferenceExpression AST node introduced.
Some tests fixed, a pair of new tests written. Kotlin code inside project fixed.
Formatter and intendation tests fixed accordingly.
Stub version is incremented.

compiler/testData/codegen/box/enum/inclassobj.kt

@@ -5,8 +5,8 @@ public class Context
         companion object
         {
                 public enum class OsType {
-                        LINUX;
-                        OTHER
+                        LINUX,
+                        OTHER;
                 }
 
                 public val operatingSystemType: OsType