soroban-cli: Nicer error when account is not funded on the network

[paulbellamy]

trafficstars

This seems like a common error devs would hit, but right now you just get:

$ soroban token create --name "foo" --symbol "FOO" --salt=100
error: jsonrpc error: RPC call failed: ErrorObject { code: InvalidRequest, message: "Resource Missing", data: None }

It would be great if we could provide a more informative error, as it took me a few minutes to figure out.

[paulbellamy]

Related: https://github.com/stellar/soroban-rpc/issues/45 https://github.com/stellar/soroban-tools/issues/142