multi: add coin selection strategy option to all on-chain rpcs

In this commit, we add the coin selection strategy option to the following
on-chain RPCs `fundpsbt`, `batchopenchannel`, `estimatefee`, `sendcoins`,
`sendmany`, and `sendoutputs`.

lnrpc/walletrpc/walletkit_server_test.go

@@ -574,6 +574,7 @@ func TestFundPsbtCoinSelect(t *testing.T) {
 			resp, err := rpcServer.fundPsbtCoinSelect(
 				"", tc.changeIndex, copiedPacket, 0,
 				tc.changeType, tc.feeRate,
+				rpcServer.cfg.CoinSelectionStrategy,
 			)
 
 			switch {