Auto merge of #3518 - str4d:3216-z_shieldcoinbase, r=str4d

Add Sapling support to z_shieldcoinbase

Part of #3216.

qa/pull-tester/rpc-tests.sh

@@ -18,7 +18,8 @@ testScripts=(
     'wallet_changeindicator.py'
     'wallet_import_export.py'
     'wallet_protectcoinbase.py'
-    'wallet_shieldcoinbase.py'
+    'wallet_shieldcoinbase_sprout.py'
+    'wallet_shieldcoinbase_sapling.py'
     'wallet_listreceived.py'
     'wallet_mergetoaddress.py'
     'wallet.py'