Add macOS ARM64 build

[basil]

Reverts cea1b32. Fixes #1371.

Testing done

With CSC_FOR_PULL_REQUEST temporarily set to true, observed the expected

  • falling back to ad-hoc signature for macOS application code signing
  • signing         file=dist/mac-arm64/Neanes.app platform=darwin type=distribution identityName=- identityHash=none provisioningProfile=none
  • skipped macOS notarization  reason=`notarize` options were unable to be generated

from electron-userland/electron-builder#9007. Downloaded the resulting .dmg file and installed to /Applications. Right-clicked and selected Open, saw "Neanes Not Opened: Apple could not verify Neanes is free of malware that may harm your Mac or compromise your privacy." (This is expected, and is better than the previous result of "damaged.") Went to Settings, Privacy & Security, saw "Neanes was blocked to protect your Mac," and clicked Open Anyway. Neanes launched and playback was fine.

[basil]

Not strictly needed for this PR, but needed for me to be able to test the CI build and seems useful more generally. Signing will not take place without setting CSC_FOR_PULL_REQUEST=true, and I used that during testing but did not retain it in the final version of this PR because of scary-looking security warnings printed to the logs. CSC_FOR_PULL_REQUEST should not be necessary for the release pipeline.

[basil]

electron-userland/electron-builder#9007