Fix targets and extra build args

[sjagoe]

This fixes #325 by building upon the fix (#327) from @VolodiaPG for build targets, adding a fix for extra build args.

With this, deploying to multiple hosts with build args works again, e.g.

../deploy-rs/target/debug/deploy -d --targets .#host1 .#host2 .#host3 --keep-result --skip-checks -- --max-jobs 0

[neunenak]

I ended up pushing a PR to fix this https://github.com/serokell/deploy-rs/pull/351 without checking to see if that had been done already. @Sntx626 what needs to happen for this fix to be mergeable?

[anna-oake]

Hey @rvem could you take a look at this long awaited fix please? 🙏 There's also #333 which is slightly different

[rvem]

LGTM, thanks for the contribution. I apologize for not responding quickly.