cl: Use bitcoin-cli to fund the wallet

Simpler than using curl+json and have to add the wallet argument.

code/docker/c-lightning/fund-c-lightning.sh

@@ -2,21 +2,12 @@
 set -Eeuo pipefail
 
 # Generate a new receiving address for c-lightning wallet
-address=$(lightning-cli --lightning-dir=/lightningd --network regtest newaddr | jq .address)
+address=$(lightning-cli --lightning-dir=/lightningd --network regtest newaddr | jq '.bech32' -r)
 
 # Ask Bitcoin Core to send 10 BTC to the address, using JSON-RPC call
-curl --user regtest:regtest \
-     -H 'content-type: text/plain;' \
-	 http://bitcoind:18443/ \
-	 --data-binary @- <<EOF
-	{
-	  "jsonrpc": "1.0",
-	  "id": "c-lightning-container",
-	  "method": "sendtoaddress",
-	  "params": [
-	    ${address},
-	    10,
-	    "funding c-lightning"
-	  ]
-	}
-EOF
+bitcoin-cli \
+    --rpcuser=regtest \
+    --rpcpassword=regtest \
+    --rpcconnect=bitcoind \
+    --regtest \
+    sendtoaddress ${address} 10 "funding c-lightning"