extract reading of public key data from ContentProvider

OpenKeychain/src/main/sqldelight/org/sufficientlysecure/keychain/KeyRingsPublic.sq

@@ -1,4 +1,9 @@
 CREATE TABLE IF NOT EXISTS keyrings_public (
-    master_key_id INTEGER PRIMARY KEY,
-    key_ring_data BLOB
-);
+    master_key_id INTEGER NOT NULL PRIMARY KEY,
+    key_ring_data BLOB NULL
+);
+
+selectByMasterKeyId:
+SELECT *
+    FROM keyrings_public
+    WHERE master_key_id = ?;