Allow adding alias when adding a contract with Dependency Manager

[chasefleming]

When adding a contract with Dependency Manager it would be nice to add a alias for a dependency. Maybe something like this:

flow deps add testnet://35717efbbce11c74.Find --alias mainnet://097bafa4e0b48eef

Additionally, it should determine the network from the address and allow you to leave the prefix off of the alias argument.

[chasefleming]

Now that #1362 introduced a prompt for adding to a deployment account it may make more sense for this to be another prompt in the flow, as opposed to a flag.