Separate flag scopes & helper methods

[antonkomarev]

Each flag has root trait Has{Name}Flag which will use:

• Has{Name}FlagScope adds global scopes to flag (and global scope related methods).
• Has{Name}FlagHelpers for additional flag methods.
• Has{Name}FlagBehavior - used only in Kept flag to implement it's default behavior (model will be created with is_kept=false and will change to is_kept=true on first model update).

[antonkomarev]

The only thing left to decide, is current methods should be placed in HasKeptFlagScope or HasKeptFlagHelpers trait.

public function scopeOnlyUnkeptOlderThanHours(Builder $builder, $hours)
{
    return $builder->onlyUnkept()
        ->where(static::getCreatedAtColumn(), '<=', Carbon::now()->subHours($hours)->toDateTimeString());
}

Right now it's in HasKeptFlagScope trait, but this is helper, not a global scope. Placed in scope because it's depends on onlyUnkept() method and if Scope trait wouldn't be loaded by developer - this method will be broken.

Solutions:

1. Left all Global Scope dependent methods in Scope trait.
2. Make this method to ignore global scope only if it's exists and used.