Add integration smoke test

[jneira]

• Tests are gonna checking that:

  • The server executables (wrapper and server itself) are downloaded
  • The hls server is started

• It uses for checking the presence of the executable files in a test path so it is adding a new option to configure where the executables are downloaded: haskell.releasesDownloadStoragePath. I think the option is useful in its own and could help to alliviate Cleanup executables from old releases #273 cause the user can point to a known directory and remove the desired obsolete versions

• It sets the log file path to check the hls server has started and has begun to write in that log

  • It has the caveat the test depends on trace.server being effective but it would fail it it does not work correctly. The only way to mask would be write the log without start the server on purpose. I hope it will not happen but we could check the content of the file to be more confident.

Closes #473

[jneira]

The macos test is working in my branch: https://github.com/jneira/vscode-haskell/runs/3837042550?check_suite_focus=true
😟

[jneira]

I can see in this pr macos log:

Unable to create basic Accelerated OpenGL renderer.

Unable to create basic Accelerated OpenGL renderer.
Core Image is now using the software OpenGL renderer. This will be slow.

That is nos present in my builds

[jneira]

I am seeing this warning in the pr jobs:

.github/workflows/test.yml : .github#L1
macOS-latest workflows will use macOS-11 soon. For more details, see https://github.com/actions/virtual-environments/issues/4060

And it is not present in my repo neither

[jneira]

Force it to use macos-11 fixed the issue indeed 🎉
We can switch to latest when all images use it (it involves changing required checks)

[berberman]

LGTM, a super nice test suite! 🎉