Fix gitlab migration unit test
Closes #1837.
The differences in dates can be explained by commit e19b9653ea, which
changed the order in which "created_date" and "updated_date" are
considered.
(cherry picked from commit b0bba20aa44e30ef0296b89f336d426224d73a16)
Mock HTTP requests in GitLab migration test
This introduces a new utility which can be added to other tests
making HTTP calls to a live service, to cache the responses of this
service in the repository.
(cherry picked from commit 52053b138948bd74c7eb88c0796c2e18f4247f3c)
Enable mocked HTTP responses for GitLab migration test
(cherry picked from commit 19cefc4de24b935a6a5c92be8360301f196f3aa5)
Simplify HTTP mocking utility in unit tests
Follow-up to https://codeberg.org/forgejo/forgejo/pulls/1841
(cherry picked from commit ca517c8bb4bf97f061b8b19fd3303d734f46660c)
(cherry picked from commit b227e0dd6bdf2dc3e8679443fc538fbce4b3bcf5)
(cherry picked from commit 6cc9d06556cda6c952a0542284fbe504114971ce)
(cherry picked from commit f0746e648dc30510d655b8a3b821199b2638800f)
(cherry picked from commit 414193341b8493723c16694789cbc08dc80b9ce5)
(cherry picked from commit 6e93df3bbb6c589502afc9dc74a7ae1a7c0f7da8)
(cherry picked from commit db0dbab5527c9f1783fd0eddb057c2d91cbb67e4)
(cherry picked from commit 8f9c9c63fbd3f266bb29d38791e83dc369cc1350)
(cherry picked from commit e74e26203095b675ccedbc2e166faed59369d467)
(cherry picked from commit 2e0933edcfa102b578fb3c2500f9e6af9e5ba1c7)
(cherry picked from commit 65060c69616631221d3dd9ef8b48fbcb007ad0c6)
