Please Export Types from @sentry/core in @sentry/react (and similar packages)

### Problem Statement

With v9, `@sentry/types` has been deprecated, with types moving into `@sentry/core`. That being said, the types are not re-exported from `@sentry/core`, so our migration path would be to install `@sentry/core` alongside `@sentry/react` just to use some of those types in our custom integration logic.

### Solution Brainstorm

Please re-export TS interfaces/types [here](https://github.com/getsentry/sentry-javascript/blob/develop/packages/react/src/index.ts#L1)