IDL: enum inheritance support

[ratoshniuk]

For example, if we need to have some generic logic for components where we need to work with same enums. It would be nice to have a chance to inhetic enums as well.

For example

module1

enum Module1FilterCondition {
    AnyField
    FieldA 
}

module2

enum Module2FilterCondition {
    AnyField
    FieldA
    FieldB 
}

in scala code, we want to perform sorting by requested fields.
And as there are two absolutely different types we need to duplicate two functions

def filterModule1EntitiesBy(filters: List[Module1FilterCondition])

def filterModule2EntitiesBy(filters: List[Module2FilterCondition])

We could have a chance to do following:

1. Define basic enum

enum BasicFiltering {
    AnyField
}

2. Inherit module 1 and 2, respectively:

enum Module1FilterCondition {
    &BasicFiltering
    FieldA 
}

module2

enum Module2FilterCondition {
    &BasicFiltering
    FieldA
    FieldB 
}

3. After that, we can provide genericFunction

def someCommonLogicOverFilteringRules[T <: BasicFiltering](t: T) : Result = ???

[ratoshniuk]

@pshirshov Or we can just create some type class and forget about what i said

[pshirshov]

It supported in V2.
You may bring it into v1 also. Should be doable.