Add simple scope management whenever a context is attached (#3159)

Add simple scope management whenever a context is attached

* 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

Author: sl0thentr0py

sentry_sdk/integrations/opentelemetry/contextvars_context.py

@@ -1,14 +1,26 @@
-from opentelemetry.context.context import Context
+from opentelemetry.context import Context, create_key, get_value, set_value
 from opentelemetry.context.contextvars_context import ContextVarsRuntimeContext
 
+from sentry_sdk.scope import Scope
+
+
+_SCOPES_KEY = create_key("sentry_scopes")
+
 
 class SentryContextVarsRuntimeContext(ContextVarsRuntimeContext):
     def attach(self, context):
         # type: (Context) -> object
-        # TODO-neel-potel do scope management
-        return super().attach(context)
+        scopes = get_value(_SCOPES_KEY, context)
+
+        if scopes and isinstance(scopes, tuple):
+            (current_scope, isolation_scope) = scopes
+        else:
+            current_scope = Scope.get_current_scope()
+            isolation_scope = Scope.get_isolation_scope()
+
+        # TODO-neel-potel fork isolation_scope too like JS
+        # once we setup our own apis to pass through to otel
+        new_scopes = (current_scope.fork(), isolation_scope)
+        new_context = set_value(_SCOPES_KEY, new_scopes, context)
 
-    def detach(self, token):
-        # type: (object) -> None
-        # TODO-neel-potel not sure if we need anything here, see later
-        super().detach(token)
+        return super().attach(new_context)