build: package docs content into npm package

[devversion]

• Packages the Bazel generated docs content into the Bazel generated ng_package of the material-examples.

Note: In a follow-up I will try to wire this up in the publish script.

[devversion]

This is ready one is ready for review. We still need to package the API overviews into the docs-content, but that one will be a follow-up.

I'm confident that packaging the docs content through Bazel will pay off in the long-term.

[jelbourn]

LGTM

[ngbot]

I see that you just added the pr: merge ready label, but the following checks are still failing:
     conflicts with base branch "master"

If you want your PR to be merged, it has to pass all the CI checks.

If you can't get the PR to a green state due to flakes or broken master, please try rebasing to master and/or restarting the CI job. If that fails and you believe that the issue is not due to your change, please contact the caretaker and ask for help.

[ngbot]

Hi @devversion! This PR has merge conflicts due to recent upstream merges.
Please help to unblock it by resolving these conflicts. Thanks!

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}