Changelog: 1600 fragment

changelog.d/1600-load-chip-key-required.md

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+- A layer that is only waiting for a key now ends the load chip on an amber
+  `KEY REQUIRED` instead of a red `LOAD FAILED`, so a keyless Environmental
+  first run no longer reports a failure while earthquakes load. A real error
+  still wins over a missing key (asturksever, #1600).