Feat/tm gitlab pagination

[y-eight]

Motivation

Referes to #230

This PR adds the ability to the GitLab targetManager to fetch files recursively in case the GitLab API provides a paginated response.

Changes

• requests for result pages are made recursively

Additional changes:

• Add helper function to get the next page link of pagination
• Increased the result per page to 30 items (default by GitLab API is 20)
• The ref is now added by the query.Set() instead of query.Add() -> result: query parameter is switched and not appended

For additional information look at the commits.

Tests done

• Unit tests succeeded
• E2E tests succeeded

TODO

• adding test case to test recursive fetchNextFileList func

[y-eight]

Test for paginated requests added.

PR is complete from my side.

[puffitos]

LGTM. I ran the sparrow with paginationPerPage set to 20 and still got 30 targets.