Add random ENUM values

[artem1458]

Added feature random-enums

[Pmyl]

Could you add some unit tests to cover the const enum case?

const enum Direction {
    Up,
    Down,
    None = 'Nothing'
}

interface Movement {
    direction: Direction;
}

[Pmyl]

I know I'm pedantic... I just created #339 due to the fact that we currently don't support enums with computed values.
Luckily computed values don't break the unit tests when mocking enums but I'm concerned about this new feature, could you try to add some tests to cover the computed values? I would like for it to not fail, since we don't support them yet they don't have to work completely, as long as the test doesn't break I'm happy with it.
We will think about adding computed values support later.
@uittorio let me know if you agree

[uittorio]

Happy with the changes. @Pmyl about computed values I agree, @artem1458 added a test as well, so when we will fix it we'll ensure that the random functionality will work as expected

Great work!!!!