Add GitHub actions for scrcpy server

[qmfrederik]

This PR adds a GitHub action which:

• Builds the latest version of the scrcpy server, using a Circle CI container
• Publishes that as a build artifact

This can be useful as CI (making sure the server compiles) and for folks that want to build the scrcpy server using CI infrastructure.

[qmfrederik]

The action won't run because it's defined in a PR, but you can see it in action here: https://github.com/qmfrederik/scrcpy/actions/runs/4097118741

[rom1v]

Thank you for your work.

There were a previous PR for github actions (#1709), but there was a problem with gradle check for an unknown reason. Can it work with with MR?

Would it be possible to build everything (server, client on linux, client on Windows…), i.e. just running ./release.sh? Or should it be done in separate jobs?

[rom1v]

Just for my information, was there a problem without it?

[qmfrederik]

build_without_gradle.sh would fail when being invoked from within a vanilla Ubuntu container. I think this is because C_LANG and friends were set to ASCII. Since this repository uses UTF-8, it seemed to make sense to enforce that here as well, and this fixed the issue.
The PR as it currently stands no longer calls build_without_gradle directly so this is not needed for this MR. I can undo the change if you want, but I don't think it's wrong ;-).

[rom1v]

Who created this image? Can we get an image with the necessary to build both the server and the client? (sorry, I'm a newbie in this domain)

[qmfrederik]

These images are generated and maintained by Circle CI, a provider of CI tooling & infrastructure. I had a look at the container images which can be used for building Android apps, and this seemed to be one of the most maintained ones. The source repo is here: https://github.com/CircleCI-Public/cimg-android.

That's a long way to say I think they are fairly trustworthy. I tried to start from ubuntu:jammy and then install ADK from the Ubuntu package repositories, but the ADK that ships with Ubuntu is too old. The other option is to start from a vanilla ubuntu:jammy image (or the vanilla image for your favorite distro) and manually install the ADK. Or not run in a container at all, but directly on the GitHub actions VM, which ship with the ADK as well: https://github.com/actions/runner-images/blob/main/images/linux/Ubuntu2204-Readme.md#android.

In general, I think you're better of using containers because it shields you from any changes on the underlying build machines.

For the app, I would recommend running the build for the app in a separate job in a separate container, as the build dependencies are quite different: the server requires the ADK, the app itself requires headers for libav*, libusb, mingw and a bunch of other dependencies.

I originally had a job which would build the client as well, but then decided against it as I didn't have the time to fully complete that work (done is better than perfect, I guess).

[yume-chan]

My dev container dockerfile is also based on cimg/android, just only contains the essential components for building Scrcpy: https://github.com/yume-chan/scrcpy-devcontainer/blob/9a7b20391574d25617241d07b75457c9f22dd1a2/.devcontainer/Dockerfile#L30-L51. The origin one needs much more disk space but it should not be an issue on CI.

[yume-chan]

I think there should also be a task to run unit tests.

Maybe cache ~/.gradle to speed up subsequent runs. Found gradle has an official GitHub action for that: https://github.com/gradle/gradle-build-action#caching