Header blurred banner on overscroll (take 2) (#5474)

* grow banner when overscrolling

* add blurview

* make backdrop blur as it scrolls

* add activity indicator

* use rotated spinner instead of arrow

* persist position of back button

* make back button prettier

* make blur less jarring

* Unify effects

* Tweak impl

* determine if should animate based on scroll amount

* sign comment

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Co-authored-by: Dan Abramov <dan.abramov@gmail.com>

package.json

@@ -120,6 +120,7 @@
     "eventemitter3": "^5.0.1",
     "expo": "^51.0.8",
     "expo-application": "^5.9.1",
+    "expo-blur": "^13.0.2",
     "expo-build-properties": "^0.12.1",
     "expo-camera": "~15.0.9",
     "expo-clipboard": "^6.0.3",