This harmonizes Swift integration tests with the rest of the repository,
to prepare for the internal integration test runner to run them. The
stripped down runner is kept compatible, so that current CI can still
use it now. Maybe it will be kept for developer use.
This PR includes:
* moving the integration tests inside `ql`
* editing `qlpack.yml` so that the internal runner can use it
* change database directory to be `test-db` rather than `db`
This way we can get logs also in case we cancelled the job due to a test
hanging indefinitely (which is happening from time to time to the Xcode
test).
Because of https://github.com/actions/runner/issues/2009 the deeply
nested action cache was failing to save the cache in the post run phase.
For the moment we just avoid the nesting with a copy-pasted action
snippet.
Previously the cache would become stale. Now the same incremental
cache mechanism in use for the QL cache is adopted (and factored out
in a separate action).
Namely, pushes on main will populate the cache using the commit hash as
key, while PRs will try to use the cache of their merge base, read-only.
To avoid the cache growing out of control, a simple cache eviction is
done on pushes.
* A unique workflow file has been created merging all `swift-*.yml`
workflows
* Change filtering at job level was added using [dorny/paths-filter][1]
* only one build of the extractor is made, and then shared via cache
(not as an artifact because of [this longstading issue][2])
* integration tests are now run on on macOS
* qltests are not run any more on macOS to cut on feedback time
* autobuilder tests were moved to the macOS build step to avoid loading
bazel twice
[1]: https://github.com/dorny/paths-filter#examples
[2]: https://github.com/actions/upload-artifact/issues/38
