Extend authorization checks

[dakr0013]

Add a new "admin" account to keycloack
Add a boolean "isAdmin" to user aggregate (default is false)
Add some kind of initializer that creates a first user when user event story is empty to create the "admin" user aggregate with "isAdmin = true"

---

Authorization Rules (Basic Set)
Companies can be created by users with "admin" flag only
All companies and their employees can be read by users with "admin" flag.
Companies and their employees can be read by users that are an employee of that company.
Employees of a company can be created and edited by users with "admin" flag or by users that are employee of that company and have the "admin" flag there.

---

Use Access Control List

• generic layout (idea: colums aggregate type, identifier, permission, user identifier)
• event handler are filling this table based on the events.
• checks are done either in interceptor or in query direct