feat: Use `globalThis` for code injection

[timfish]

Since v8 of the JavaScript SDKs we dropped Node v12 support which means all the platforms we support have globalThis.

This saves ~90 bytes every time debug IDs are injected.

• SDKs read from globalThis - https://github.com/getsentry/sentry-javascript/pull/11351
• Next.js SDK injects globalThis - https://github.com/getsentry/sentry-javascript/pull/13132
• Bundler plugins inject globalThis - https://github.com/getsentry/sentry-javascript-bundler-plugins/pull/610

@lforst points out that this would require a major version bump of both the CLI and the bundler plugins so these bumps would likely need to occur at the same time and it might not be a priority to merge this straight away!