lnrpc+lncli: adds required reserve rpc & cli

lnrpc/walletrpc/walletkit.yaml

@@ -55,6 +55,8 @@ http:
       body: "*"
     - selector: walletrpc.WalletKit.ListAccounts
       get: "/v2/wallet/accounts"
+    - selector: walletrpc.WalletKit.RequiredReserve
+      get: "/v2/wallet/reserve"  
     - selector: walletrpc.WalletKit.ImportAccount
       post: "/v2/wallet/accounts/import"
       body: "*"