Feature: add an `identity` block to the root module

[kimfy]

Feature Description

Configuring the workload identity using a identity {} block would be more structured and organized than how it is today.

Problem and Motivation

Adding more configuration options for the identity would require us to expand the root module instead of a object.

Possible Implementation

Caller:

module "station" {
  identity = {
    name = "example"
    role_assignments = {...}
    directory_role_assignment = {...}
  }
}