Add contract alias show.

[fnando]

What

$ cargo run contract alias show increment --network testnet --global
   Compiling soroban-cli v21.4.1 (/Users/fnando/Projects/stellar/stellar-cli/cmd/soroban-cli)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 3.05s
     Running `target/debug/soroban contract alias show increment --network testnet --global`
ℹ️ Contract alias 'increment' references CALLOOCCCJRZ6AZAJSKNCTDZ766N4ANVRKRJPHC65KDV7RJCS37PS4XY on network 'Test SDF Network ; September 2015'
CALLOOCCCJRZ6AZAJSKNCTDZ766N4ANVRKRJPHC65KDV7RJCS37PS4XY

$ cargo run contract alias show increment --network testnet --global > /tmp/id.txt
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.21s
     Running `target/debug/soroban contract alias show increment --network testnet --global`
ℹ️ Contract alias 'increment' references CALLOOCCCJRZ6AZAJSKNCTDZ766N4ANVRKRJPHC65KDV7RJCS37PS4XY on network 'Test SDF Network ; September 2015'

$ cat /tmp/id.txt
CALLOOCCCJRZ6AZAJSKNCTDZ766N4ANVRKRJPHC65KDV7RJCS37PS4XY

$ cargo run contract alias show hello --network testnet --global
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.18s
     Running `target/debug/soroban contract alias show hello --network testnet --global`
error: no contract found with alias `hello`

Why

#1420

Known limitations

N/A

[willemneal]

Just one question

[leighmcculloch]

👏🏻 The split of user friendly message on stderr along with outputting the contract addresses to stdout is 👨🏻‍🍳💋.