--base-directory flag name is misleading

[verythorough]

netlifyctl deploy has a --base-directory flag that sets the directory to be published.

In the Netlify UI and the netlify.toml config, this directory is called Publish. In the netlify.toml config, base refers to something different - namely, the root of the project, where Netlify expects to find files like package.json.

The inconsistency of the --base-directory flag name causes confusion about its purpose. I suggest renaming it to something like --publish-directory (though it would need a different shortcut than -p, since that's taken by `--preprocess).

If changed, it would be nice to keep --base-directory as an undocumented fallback, so that previously configured environments don't break when running the new version.