[WebUI] Implement API Token Authentication in WebUI

[hamidonos]

Situation

Currently the API Token is not used for authentication inside the SecHub WebUI.

Wanted

We want to enable API Token authentication so that users can either log in with OAuth2 or API Token.

Solution

• Add Basic Auth login api to SecHub WebUI
• Upon login attempt the WebUI Backend calls the SecHub Server to validate the Basic Auth Credentials
• Make sure the API Token is set in the cookies (encrypted) after successful authentication
• That way we ensure that the user is not logged out in the next request
• The cookie should be alive for the 24h (configured by the backend)