chore(server): Github Branches Webhook & Rest & Controller

[TurkerKoc]

Motivation

Description

Testing Instructions

Prerequisites:

• GitHub Account without having any additional access-rights (e.g. admin, owner)
• ...

Flow:

1. Log in to Helios as a Developer
2. Navigate to Settings
3. ...

Screenshots

Checklist

General

• PR description explains the purpose and changes. (f.e. following the 'Conventional Commits')
• Changes have been tested locally.
• Screenshots have been attached.

Server

• Code is performant and follows best practices
• I documented the Java code using JavaDoc style.

Client

• I documented the TypeScript code using JSDoc style.
• I added multiple screenshots/screencasts of my UI changes.
• I translated all newly inserted strings into English and German.