feat: deprecate --unsigned flag in favor of --default-signer for forc-deploy/run

[kayagokalp]

Description

This PR deprecates --unsigned flag in favor of --default-signer. The reasoning is the following:

The reason forc-deploy was offering --unsigned flag was enabling users to create deployment transactions agains their local node without going through wallet funding steps, an ease of development & testing. There are some accounts funded by fuel-core by default, we can still offer the same seamless deployment to local node by signing them with one of these default accounts. So after this PR we can use the following command to deploy to a local node without going through any manual signing/funding steps:

forc-deploy --default-signer

 Compiling library core (/Users/kayagokalp/.forc/git/checkouts/std-9be0d6062747ea7/241d30f7cde5cdd1f378eb2bc1daae945f329d0c/sway-lib-core)
 Compiling library std (git+https://github.com/fuellabs/sway?tag=v0.44.0#241d30f7cde5cdd1f378eb2bc1daae945f329d0c)
 Compiling contract target-deploy (/Users/kayagokalp/fuel/test_projects/target-deploy)
  Finished debug in 4.496855625s
  contract target-deploy
      Bytecode size: 68 bytes


Contract target-deploy Deployed!

Network: http://127.0.0.1:4000
Contract ID: 0xed71e83b4783f463b9cf4ccd29818d2855878c241c7c957cafa6eb36d543122d
Deployed in block 0xb640ef91c7e988cd5d79efbae433eb970b5d7fc13ad49c6b6554795849edbaaa

We are still keeping the --unsigned flag to make sure anyone depending on it does not break out of no where but we print an explicit warning alongside it. Basically it is now aliased to --default-signer by default and should be removed completely after giving downstream enough time to settle.

forc-deploy --unsigned

 Warning: --unsigned flag is deprecated, please prefer using --default-signer. Assuming `--default-signer` is passed. This means your transaction will be signed by an account that is funded by fuel-core by default for testing purposes.
 Compiling library core (/Users/kayagokalp/.forc/git/checkouts/std-9be0d6062747ea7/241d30f7cde5cdd1f378eb2bc1daae945f329d0c/sway-lib-core)
 Compiling library std (git+https://github.com/fuellabs/sway?tag=v0.44.0#241d30f7cde5cdd1f378eb2bc1daae945f329d0c)
 Compiling contract target-deploy (/Users/kayagokalp/fuel/test_projects/target-deploy)
  Finished debug in 4.63308225s
  contract target-deploy
      Bytecode size: 68 bytes


Contract target-deploy Deployed!

Network: http://127.0.0.1:4000
Contract ID: 0xf969a84f0351033de85d9867c68d1b3ae122ff26de858441aef9d60f2a8ba45f
Deployed in block 0x8ebd8ba5c88bb4ed05d854a40a7e6b6aa582d03d2c947189ea631e58a08eabc5

[sdankel]

LGTM

[JoshuaBatty]

utACK, thanks :)