* create a new otel context `_SCOPES_KEY` that will hold a tuple of
  `(curent_scope, isolation_scope)`
* the `current_scope` will always be forked (like on every span creation/context update in practice)
  * note that this is on `attach`, so not on all copy-on-write context
    object creation but only on apis such as
    [`trace.use_span`](https://github.com/open-telemetry/opentelemetry-python/blob/ba22b165471bde2037620f2c850ab648a849fbc0/opentelemetry-api/src/opentelemetry/trace/__init__.py#L547)
    or [`tracer.start_as_current_span`](https://github.com/open-telemetry/opentelemetry-python/blob/ba22b165471bde2037620f2c850ab648a849fbc0/opentelemetry-api/src/opentelemetry/trace/__init__.py#L329)
  * basically every otel `context` fork corresponds to our `current_scope` fork
* the `isolation_scope` currently will not be forked
  * these will later be updated, for instance when we update our top
    level scope apis that fork isolation scope, that will also have a
    corresponding change in this `attach` function