Integrate automated CI/CD with custom domain support

[alexander-potemkin]

I've noticed that Element releases and builds are deployed to the AppStore & Play Market manually. Could you be interested in merging both iOS and Android builds systems?

Here are mostly working automated builds for:

• iOS
• Android
• Desktop

All of those github actions support custom domain / domain replacement during the build, so I believe it could be useful in many of the Element and side projects.

I understand that currently iOS releases are, most probably, build and published manually, but if every commit to main will build and deploy a new release to TestFlight, you can save your time and just let a tested release to go to the production with a few clicks of the mouse.

Our Android & Desktop builds are pretty much stable, but iOS one got broken on a recent Ruby extension upgrade and then we got stuck with unclear lint errors - that was the moment I realized that we want that to be part of the project as soon as possible, to make sure we are still in line with the actual product.