fix: removing core lib exports from root index

[kallebysantos]

What kind of change does this PR introduce?

Bug fix

What is the current behavior?

core lib exports are available from package root @supabase/server

What is the new behavior?

core lib exports are only available from @supabase/server/core

Additional context

Towards FUNC-528

[linear]

FUNC-528 Fix package default exports

Currently I am able to import primitives from root:

import {
  verifyAuth,
  createContextClient,
  createAdminClient,
} from '@supabase/server'

And it should be from /core:

import {
  verifyAuth,
  createContextClient,
  createAdminClient,
} from '@supabase/server/core'