Injected global variable `_global` can clash with user code

[timfish]

We inject code that creates a new variable called _global:

sentry-javascript-bundler-plugins/packages/bundler-plugin-core/src/utils.ts

Lines 317 to 329 in b2a0529

	let code = `
	var _global =
	typeof window !== 'undefined' ?
	window :
	typeof global !== 'undefined' ?
	global :
	typeof globalThis !== 'undefined' ?
	globalThis :
	typeof self !== 'undefined' ?
	self :
	{};
	_global.SENTRY_RELEASE={id:${JSON.stringify(release)}};`;

There is a chance this can clash with user code if that variable name is used.

We should either chose a variable name that is more unique and less likely to clash with user code or wrap this code block in a closure so that the scope is private.