Provide common workspace setup

Provide a common importable function to setup the `WORKSPACE` for downstream repositories, retrieving necessary dependencies and setting up things like node modules.

This would allow us to sychronize the versions of node and rules_nodejs being used by repositories.

Before:
```py
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

# Fetch rules_nodejs so we can install our npm dependencies
http_archive(
name = "build_bazel_rules_nodejs",
sha256 = "5c40083120eadec50a3497084f99bc75a85400ea727e82e0b2f422720573130f",
urls = ["https://github.com/bazelbuild/rules_nodejs/releases/download/4.0.0-beta.0/rules_nodejs-4.0.0-beta.0.tar.gz"],
)

load("@build_bazel_rules_nodejs//:index.bzl", "node_repositories", "yarn_install")

node_repositories(
node_repositories = {
"14.17.0-darwin_amd64": ("node-v14.17.0-darwin-x64.tar.gz", "node-v14.17.0-darwin-x64", "7b210652e11d1ee25650c164cf32381895e1dcb3e0ff1d0841d8abc1f47ac73e"),
"14.17.0-linux_amd64": ("node-v14.17.0-linux-x64.tar.xz", "node-v14.17.0-linux-x64", "494b161759a3d19c70e3172d33ce1918dd8df9ad20d29d1652a8387a84e2d308"),
"14.17.0-windows_amd64": ("node-v14.17.0-win-x64.zip", "node-v14.17.0-win-x64", "6582a7259c433e9f667dcc4ed3e5d68bc514caba2eed40e4626c8b4c7e5ecd5c"),
},
node_version = "14.17.0",
)

yarn_install(
name = "npm",
package_json = "//:package.json",
yarn_lock = "//:yarn.lock",
)
```

After:
```py
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

# Fetch rules_nodejs so we can install our npm dependencies
http_archive(
name = "angular-dev-infra",
sha256 = "...",
urls = ["https://github.com/angular/dev-infra-private-builds/..."],
)
```

Inizia con l'esempio WORKSPACE e gli input package.json e yarn.lock a cui si fa riferimento, quindi segui il modo in cui i repository downstream caricano attualmente rules_nodejs, node_repositories e yarn_install. Il lavoro è completato quando i repository downstream possono importare una configurazione condivisa del workspace e sincronizzare le proprie versioni di Node e rules_nodejs senza ripetere la configurazione mostrata.

Scritto dal modello di indicizzazione a partire dal testo della issue.