feat: change endpoint of AnnotationAPI

Feature

Summary

This MR provides a new endpoint declaration of the AnnotationAPI which is now served at /api/annotations instead of /api/textapi.

Compliance to “Definition of Done”

• Unit tests passed
• Code reviewed
• Acceptance criteria met
• Functional tests passed
• Non-Functional requirements met
• Product Owner accepts the User Story

Documentation

• I updated existing documentation

Tests

Are we able to test this new feature?

• Yes, everything can be done via unit tests.

Changelog

• I added a statement to the CHANGELOG.

Version number

• I bumped the version number in build.properties.

Related Tickets

Closes

Closes #69 (closed).

/cc Mathias Göbel, Frank Schneider, Michelle Weidling