integrations: basic test for Gitea {dump,restore}-repo
This is a first step for integration testing of DumpRepository and
RestoreRepository. It:
runs a Gitea server,
dumps a repo via DumpRepository to the filesystem,
restores the repo via RestoreRepository from the filesystem,
dumps the restored repository to the filesystem,
compares the first and second dump and expects them to be identical
The verification is trivial and the goal is to add more tests for each
topic of the dump.
Signed-off-by: Loïc Dachary <loic@dachary.org>