feat: introduce Cargo extension CLI for creating packages for building programs

[DennisInSky]

This PR introduces a binary crate which can be registered as a Cargo extension with the following command line

Usage: cargo-sails new-program [OPTIONS] <PATH>

Arguments:
  <PATH>  Path to the new program

Options:
  -n, --name <NAME>  Name of the new program
      --with-client  Generate client crate alongside the program
      --with-gtest   Generate program tests using 'gtest'. Implies '--with-client'
  -h, --help         Print help

The --with-client and --with-gtest options are not implemented yet and generated program contains some stubs for both client and gtest testing

Resolves #448 .