scripted-diff: Rename PACKAGE_* variables to CLIENT_*

This change ensures consistent use of the `CLIENT_` namespace everywhere
in the repository.

-BEGIN VERIFY SCRIPT-

ren() { sed -i "s/\<$1\>/$2/g" $( git grep -l "$1" ./cmake ./src :\(exclude\)./src/secp256k1 ./test ) ; }

ren PACKAGE_NAME      CLIENT_NAME
ren PACKAGE_VERSION   CLIENT_VERSION_STRING
ren PACKAGE_URL       CLIENT_URL
ren PACKAGE_BUGREPORT CLIENT_BUGREPORT

-END VERIFY SCRIPT-

test/functional/interface_bitcoin_cli.py

@@ -375,7 +375,7 @@ class TestBitcoinCli(BitcoinTestFramework):
         self.log.info("Test -version with node stopped")
         self.stop_node(0)
         cli_response = self.nodes[0].cli('-version').send_cli()
-        assert f"{self.config['environment']['PACKAGE_NAME']} RPC client version" in cli_response
+        assert f"{self.config['environment']['CLIENT_NAME']} RPC client version" in cli_response
 
         self.log.info("Test -rpcwait option successfully waits for RPC connection")
         self.nodes[0].start()  # start node without RPC connection