git-remote-mediawiki (t9361): test git-remote-mediawiki pull and push

git-remote-mediawiki (t9361): test git-remote-mediawiki pull and push

This patch provides a set of tests for the pull and push fonctionnality
of git-remote-mediawiki. The actual tests are kept in a separate function
to allow further tests to re-run the same set of commands with different
push and pull strategies.

Signed-off-by: Simon CATHEBRAS <redacted>
Signed-off-by: Julien KHAYAT <redacted>
Signed-off-by: Simon Perrat <redacted>
Signed-off-by: Charles ROUSSEL <redacted>
Signed-off-by: Guillaume SASDY <redacted>
Signed-off-by: Matthieu Moy <redacted>
Signed-off-by: Junio C Hamano <redacted>