Add native backend support for Mac

[tustanivsky]

This PR adds opt-in support for the sentry-native backend on macOS. When enabled, macOS uses the same sentry-native (GenericPlatform) implementation as Windows and Linux instead of the default sentry-cocoa SDK. This also enables the external crash reporter on macOS, which requires the native backend.

[github-actions]

Semver Impact of This PR

⚪ None (no version bump detected)

📋 Changelog Preview

This is how your changes will appear in the changelog.
Entries from this PR are highlighted with a left border (blockquote style).

---

Bug Fixes 🐛

• Prevent potential script injection in crash-reporter-build workflow by fix-it-felix-sentry in #1324

Internal Changes 🔧

Deps

• Update Native SDK to v0.13.5 by github-actions in #1334
• Update Cocoa SDK to v9.9.0 by github-actions in #1332
• Update CLI to v3.3.5 by github-actions in #1323

Other

• Update validate-pr workflow by stephanie-anderson in #1328

Other

• Add native backend support for Mac by tustanivsky in #1333

• Fix intermittent crash when capturing screenshots due to invalid viewport by tustanivsky in #1331
• Suppress superfluous warnings when detecting for SteamOS by yangskyboxlabs in #1326
• Add out-of-process screenshot capturing on Windows by tustanivsky in #1325

---

_{🤖 This preview updates automatically when you update the PR.}

[github-actions]

	Messages
📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

Generated by 🚫 dangerJS against fc9a770