profiling-node should store profile_id on span rather than profile context

[timfish]

Description

Currently @sentry/profiling-node stores the profile_id on the isolated context:

sentry-javascript/packages/profiling-node/src/integration.ts

Line 87 in ec02f84

getIsolationScope().setContext('profile', { profile_id });

This means the profile cannot be found if there are multiple versions of @sentry/core in the dependencies.

Instead can we store the profile_id on the span? There's already a property for this:

sentry-javascript/packages/core/src/types-hoist/span.ts

Line 49 in bfe7bfa

profile_id?: string;

Then the integration wouldn't rely on updating any scope. In the beforeEnvelope hook we just go through the spans until we find a profile_id?