feat(core): Add user to logs

[AbhiPrasad]

resolves https://linear.app/getsentry/issue/JS-294

ref https://develop.sentry.dev/sdk/telemetry/logs/#user-attributes

[Lms24]

l/also fine as follow-up: Wdyt about making this a utility function? We have very similar logic in our event processing pipeline

sentry-javascript/packages/core/src/utils/prepareEvent.ts

Lines 82 to 93 in 56137a8

	const data = getGlobalScope().getScopeData();
	if (isolationScope) {
	const isolationData = isolationScope.getScopeData();
	mergeScopeData(data, isolationData);
	}
	if (finalScope) {
	const finalScopeData = finalScope.getScopeData();
	mergeScopeData(data, finalScopeData);
	}

as well as in Node ANR (though admittedly I don't care much about the bundle size there)

might save some bytes and it might help us get rid of the complexity eslint comment (though again, low prio obviously)

[mydea]

also can we rename this to e.g. getMergedScopeData() or something like this, was not clear to me from the function name that this would consider isolation scope etc :)

[AbhiPrasad]

Will think about the utility function as a follow up