[stub-server] Add possible to configure checking Authorization header

[mironx]

Add possibility to enable checking and configuration of Authorization header

Endpoints to configure stubserver to enable authorization:

• POST /stubserver/auth/enable – Enables authorization header verification.
• POST /stubserver/auth/disable – Disables authorization header verification.
• PUT /stubserver/auth/header – Sets or updates the expected authorization header.
• GET /stubserver/auth/status – Retrieves the current authorization configuration (enabled/disabled, expected header).

When authorization is enabled, any API request outside of /stubserver/ must include the correct authorization header.

Would be good to implement after:
#62