Bugfix blueprint naming

Following discussions for Flask we've decided to name blueprints based
on how they are registered. This allows for two different blueprints
to have the same self-name as long as they are registered in different
nested positions. This helps users choose better blueprint names.

src/flask/wrappers.py

@@ -1,6 +1,7 @@
 import typing as t
 
 from werkzeug.exceptions import BadRequest
+from werkzeug.utils import cached_property
 from werkzeug.wrappers import Request as RequestBase
 from werkzeug.wrappers import Response as ResponseBase
 
@@ -77,6 +78,21 @@ class Request(RequestBase):
         else:
             return None
 
+    @cached_property
+    def blueprints(self) -> t.List[str]:
+        """The names of the current blueprint upwards through parent
+        blueprints.
+        """
+        if self.blueprint is None:
+            return []
+
+        bps: t.List[str] = [self.blueprint]
+
+        while "." in bps[-1]:
+            bps.append(bps[-1].rpartition(".")[0])
+
+        return bps
+
     def _load_form_data(self) -> None:
         RequestBase._load_form_data(self)