Add native Apple Silicon target to build workflow

On every release tag and manual trigger when the "Include builds on non-free runners" checkbox is checked, make the
Arduino IDE build for native Apple Silicon host in addition to the builds that are always generated by the "Arduino IDE"
GitHub Actions workflow.

Previously, the build workflow only produced a build for x86-64 (AKA "Intel") macOS hosts. Although it is possible to
use those builds on Apple Silicon machines via the Rosetta 2 translation software, the performance is significantly
inferior to a native build. The reason we produced those Apple Silicon builds manually instead of via the same automated
continuous deployment system as the other builds was that GitHub did not provide the necessary Apple Silicon runner
machines and Arduino was not capable of setting up such self-hosted machines in a manner that would make them feasible
for the project maintainers to use. For this reason, the native Apple Silicon builds had to be produced and published
manually. GitHub hosted Apple Silicon runner machines are now available so we can add the target to the build workflow.

GitHub gives unlimited use of the basic runner machines for workflow runs in public repositories. However, the macOS ARM
architecture is only provided in runner machines which are classified as "larger runner". Use of these runners is
charged on a per-minute basis, without any of the free allowances GitHub provides for the normal runners. In order to
avoid unnecessary expenditures, native Apple Silicon builds must be generated only when there is compelling reason to do
so. Such a build is needed for every release, so the workflow is configured to always generate the builds when triggered
by a tag. In addition to releases, Apple Silicon tester builds for pull requests that might have special implications
for this target. For this reason, the workflow is configured to allow Apple Silicon builds to be triggered manually by a
repository maintainer.

Author: per1234