`Enum` type instead of define multiple constant variable

[ZigBalthazar]

regarding to Tact book constants documentation, it defined a non-friendly way to use the Enum concepts in Tact. developers should define multiple constants instead of an enum, this way has some problem:

1. the defined constants to use instead of enums do not have a group: it means if we have to define an enum for the status of a user we should do this for now:

   const activeUser: Int = 0;
   const blockUser: Int = 1;
   const deletedUser: Int = 2;

   there is no consistency in naming and grouping. maybe it be better to do this like it(just syntax sample):

   enum user_status {
   ACTIVE = 0,
   BLOCK = 1,
   DELETED = 2
   }

   or

   const (
   userActive = 0
   userBlock = 1
   userDeleted = 2
   )

2. type consistency: based on the above example from the tact book it is a mistake potential to use constant instead of enum for types, for example:

   const activeUser: Int = 0;
   const blockUser: string = "1";
   const deletedUser: Int = 2;

Let's consider a solution for the mentioned problem by defining an enum type for tact and the tact compiler to make the tact language more developer-friendly. We can take inspiration from other languages, such as TypeScript, which changed the syntax and defined the enum type, while Golang used const in a grouping manner. There are various ways to implement this, and we should have a detailed discussion about the implementation of this feature in this issue.

[anton-trunov]

Duplicate of #17