Use the `.gitlab` folder for configuration file and update file name

Problem

API Fuzzing stores the configuration file by default in the root of the repository. There is a convention for storing configuration under a .gitlab directory. https://docs.gitlab.com/ee/development/features_inside_dot_gitlab.html

Proposal

Switch the default configuration file location to the .gitlab/ folder.

• For fuzzing mode change default location from .gitlab-api-fuzzing.yml to .gitlab/gitlab-api-fuzzing-config.yml,
• and for dast mode change default location from .gitlab-dast-api.yml to .gitlab/gitlab-dast-api-config.yml

Tasks:

1. Update worker-entry to fall back on old location for configuration file.
2. Update tests to use new location
   1. Add a test to verify new location works (.gitlab/) for fuzzing and dast mode
   2. Add a test to verify old location works for fuzzing and dast modes
   3. Update the e2e tests to use the new location
   4. Add a new e2e test that uses the old location
3. [-] Change default in CI template !59146 (closed) !59173 (closed)
4. Update entry points in SDK.
5. Update the documentation !54018 (merged)
6. Update example projects