Add xtask for cross-compiling and running over an SSH target

[MatteoNardi]

I've added an xtask which, given a target triplet, cross compiles a binary and executes it over an SSH target.
This is just a shortcut for commonly executed commands.

$ cargo xtask cross --help
Cross compile and run on the specified target

Usage: xtask cross [OPTIONS] <COMMAND>

Commands:
  build  Build binary and copy it to destination folder
  run    Run over the given SSH connection

Options:
      --target <TARGET>  Target architecture [default: x86_64-unknown-linux-musl]
      --binary <BINARY>  Binary to compile [default: test-suite]
  -h, --help             Print help

It's just a shortcut for running cross, llvm-strip, scp and executing the binary over ssh.

I have

• run cargo fmt;
• run cargo clippy;
• run cargo testand all tests pass;
• linked to the originating issue (if applicable).

[banditopazzo]

sorry for keeping you waiting for the review so long

[banditopazzo]

LGTM