Improve CI Script

[IntegerLimit]

This PR improves the current CI buildscript, by adding three new features:

1. A revised and improved Linux Arm build, using the new GitHub native Linux Arm runners, greatly improving speed;
2. Building a Mac Universal Binary automatically;
3. Uploading all built binaries as artefacts, so that users can easily test and run the latest state of any branch (especially master), without compiling it themselves

[bqminh]

looks good!