rustup and wasm32-unknown-unknown auto setup

[volovyks]

Tested on Linux (Arch + Bash/ZSH)
Latest Mac OS (ZSH)
Windows 10 (Power Shell)

It will be great to run it on your PC. Don't forget to clear .bashrc, .zshenv, etc., and make sure that cargo is not in the PATH before the test.

Example:

node ../create-near-app/index.js coolApp --contract=rust
...[some boilerplate here]...
Checking if rustup is installed...
rustup is not installed


In order to work with rust smart contracts we recommend you install rustup, the Rust toolchain installer. We can run the following command to do it for you:

    curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y

Continue with installation (Y/n)?: y
Installing rustup...

...[some boilerplate from Rust]...

Checking installed Rust targets..
x86_64-unknown-linux-gnu
wasm32-unknown-unknown target  is not added

To build Rust smart contracts you need to add WebAssembly compiler target to Rust toolchain. We can run the following command to do it for you:

    rustup target add wasm32-unknown-unknown

Continue with installation (Y/n)?: y
Adding wasm32-unknown-unknown target...

...[more Rust and js boilerplate]...

Success! Created coolApp
Inside that directory, you can run several commands:

  yarn dev
    Starts the development server. Both contract and client-side code will
    auto-reload once you change source files.

  yarn test
    Starts the test runner.

  yarn deploy
    Deploys contract in permanent location (as configured in src/config.js).
    Also deploys web frontend using GitHub Pages.
    Consult with README.md for details on how to deploy and package.json for full list of commands.

We suggest that you begin by typing:

    source $HOME/.cargo/env
    cd coolApp
    yarn dev

Happy hacking!

[vgrichina]

lgtm besides few nits

disclaimer: I didn't test whether works alright

[chadoh]

Can you put an example of what this complete interaction looks like (as a screenshot or copy-pasted text) in the description of this PR, please?

[chadoh]

One more nit, see below, and I also noticed that the rust-setup.js file has four-space indents instead of 2 like the rest of the project. This project even has a .editorconfig file that specifies two-space indents. Please configure your editor to honor this file.

But these are small things, and I don't need to review this PR again once you address them. This change looks great and it'll make a big difference for newbie NEARies who want to use Rust! Thank you!