This patch introduces reusable workflow used by integration testing
machinery run within tarantool/luajit repository.

For the first attempt GitHub action has been used, but its fetch (or
more precisely unpack) phase fails due to test/test-run.py symlink into
test-run submodule (the action being used doesn't fetch it while packing
tarantool repository). As the alternative for removing this symlink, it
was decided to use reusable workflows despite its known limitations
(e.g. inability to use the testing matrix) until the issue with symlink
is resolved in any possible way.

As an alternate way, a common action to be used in all submodules for
integration testing can be added to tarantool/actions repository.

NO_DOC=ci
NO_TEST=ci
NO_CHANGELOG=ci

Reviewed-by: Yaroslav Lobankov <y.lobankov@tarantool.org>
Reviewed-by: Sergey Bronnikov <sergeyb@tarantool.org>
Signed-off-by: Igor Munkin <imun@tarantool.org>