build: remove native mksnapshot for arm/arm64

[jkleinsc]

Description of Change

Starting with Chromium 74, we can no longer build native mksnapshot binaries for arm and arm64. The decision was made by the @electron/wg-upgrades Working Group to deprecate these binaries for 5-0-x with the intention of removing them completely for 6-0-x.

This PR removes those binaries from our build and from the release. Also to make sure snapshots still work on arm/arm64, CI has been updated to create arm/arm64 snapshots using the x64 binary that are then tested on arm/arm64 hardware.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• tests are changed or added
• PR title follows semantic commit guidelines
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Removed native mksnapshot binaries for arm/arm64 as they no longer work.

[nornagon]

Can we remove the patches also?

[jkleinsc]

Thanks for the reminder @nornagon. I was planning on removing them but forgot to do so. They are now removed as part of this PR.

[nornagon]

Looks like the linux build is failing though?

[jkleinsc]

@nornagon I had started work on this in another branch and must have missed a commit. The latest commit should fix the linux build.

[nornagon]

Aha, I thought there ought to be more red lines! Thanks :)

[jkleinsc]

Merging as mac failure was flake and it reran successfully here: https://circleci.com/gh/electron/electron/165267

[release-clerk]

Release Notes Persisted

Removed native mksnapshot binaries for arm/arm64 as they no longer work.