Previously, when one wanted to try out the changes from a PR before it
was merged, they had to check out the PR locally and build the Angular
packages themselves (which is time-consuming and wasteful given that the
packages have already been built on CI).
This commit persists all Angular packages on each build as `.tgz` files,
which can be used to install dependencies on an project (supported by
both [npm][1] and [yarn][2]). In addition to individual `.tgz` files for
each package, a `.tgz` file including all packages is also stored, which
can be used to test the packages locally by overwriting the ones in the
`node_modules/` directory of a project.
CircleCI [build artifacts][3] an be used for longer-term storage of the
outputs of a build and are designed to be useful around the time of the
build, which suits our needs.
[1]: https://docs.npmjs.com/cli/install.html
[2]: https://yarnpkg.com/lang/en/docs/cli/add
[3]: https://circleci.com/docs/2.0/artifacts
PR Close#33321
efbbae5a48