Cargo npk subcommand

[flxo]

Think about implementing a cargo subcommand for building npks from Rust crates. e.g

cargo npk --bin <bin> --release --root res/root --manifest res/manifest.yaml ....

The manifest could also be merged with the cargo manifest

[package]
name = "hello-world"
version = "0.1.0"
authors = ["ESRLabs"]
edition = "2021"
license = "Apache-2.0"


[package.metadata.npk]
version = "0.0.1"
init = "/hello-world"
uid = 1000
gid = 1000

Consider using xtask in order to get cross build with the support of cross.

See cargo-deb as reference.