Add support for --base CLI argument

[natemoo-re]

Changes

• Astro currently allows --site and --root and a few other CLI arguments.
• This PR adds support for --base as well
• Why? Sometimes CLI arguments are very handy, like if you're building an official GitHub Action (withastro/action) and want to automatically pass in the --site and --base that GitHub already knows.

See also actions/configure-pages#30

Testing

Tested manually because we don't have equivalent tests for --site or other arguments

Docs

withastro/docs#1646
/cc @withastro/maintainers-docs

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[tony-sull]

Nice! Might be worth adding a CLI log that could be checked by a test as well if the CLI tests are in a decent spot for it, but not 100% necessary 👍

[sarah11918]

Removing the docs-maintainers review, as the changes to @types/astro.ts won't affect docs!

[jasikpark]

can you update astro help for these?

❯ npx astro build --help

   astro  v1.4.0 Build faster websites.

  astro [command] [...flags]

   Commands 
              add  Add an integration.
            build  Build your project and write it to disk.
            check  Check your project for errors.
              dev  Start the development server.
             docs  Open documentation in your web browser.
          preview  Preview your build locally.
        telemetry  Configure telemetry settings.

   Global Flags 
  --config <path>  Specify your config file.
    --root <path>  Specify your project root folder.
        --verbose  Enable verbose logging.
         --silent  Disable all logging.
        --version  Show the version number and exit.
           --help  Show this help message.

interesting that astro build -h doesn't print help & just builds
i would have expected that you can drill into build-specific flags w/ astro help build or astro build --help

[natemoo-re]

Thanks @jasikpark! Updated the help command output. Would you mind opening a new issue for tracking astro build --help?

[jasikpark]

does this classify as a bug report? since that's the only type of issue in "new issue" that creates an actual issue?

[jasikpark]

Thanks @jasikpark! Updated the help command output. Would you mind opening a new issue for tracking astro build --help?

#4935

[matthewp]

Seems like this should be a minor

[matthewp]

Think this is a minor change.

[github-actions]

This PR is blocked because it contains a minor changeset. A reviewer will merge this at the next release if approved.

[matthewp]

lgtm for next minor

[matthewp]

@natemoo-re can you fill out the changeset a bit more? Something like a paragraph, maybe a code example, so that this could be copy/pasted into a blog post. Thank you!

Today is merge day

[github-actions]

This PR is blocked because it contains a minor changeset. A reviewer will merge this at the next release if approved.

Today is merge day